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习题练习:Sequences & Series

 作者: admin 发布日期: 2024-06-02 22:00   总分: 65分  得分: _____________

答题人: 游客未登录  开始时间: 23年04月20日 23:31  切换到: 整卷模式

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1#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Consider an arithmetic e066giuzhij7v dl9n/v j7*ldsequence 2,6,10,14, $\ldots $
1. Find the common difference, d .   
2. Find the 10th term in the sequence.   
3. Find the sum of the first 10 terms in the sequence.   

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2#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An arithmetic sequence h 6u9cvy 0wvpxvcig 2sxl.6z:1 as $u_{1}=40, u_{2}=32, u_{3}=24$ .
1. Find the common difference, d .   
2. Find $u_{8}$ .   
3. Find $S_{8}$ .   

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3#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Only one of the followinq+uww 5quwa q5x -)5beg four sequences is arithmetic and only one of them is geometa+wu 5xu-5bqew qw q5)ric.

$\begin{aligned}
a_{n} & =1,5,10,15, \ldots & c_{n} & =1.5,3,4.5,6, \ldots \\
b_{n} & =\frac{1}{2}, \frac{2}{3}, \frac{3}{4}, \frac{4}{5}, \ldots & d_{n} & =2,1, \frac{1}{2}, \frac{1}{4}, \ldots
\end{aligned}$

1. State which sequence is arithmetic and find the common difference of the sequence.
2. State which sequence is geometric and find the common ratio of the sequence.
3. For the geometric sequence find the exact value of the eighth term. Give your answer as a fraction.
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4#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Only one of the following four sequences is arithmetic and only5(z+7 wjnzr a +pmk9if one of them is geometri9j ianr (w7p5k+zf +zmc.

$\begin{aligned}
a_{n} & =\frac{1}{3}, \frac{1}{4}, \frac{1}{5}, \frac{1}{6}, \ldots & c_{n} & =3,1, \frac{1}{3}, \frac{1}{9}, \ldots \\
b_{n} & =2.5,5,7.5,10, \ldots & d_{n} & =1,3,6,10, \ldots
\end{aligned}$

1. State which sequence is arithmetic and find the common difference of the sequence.
2. State which sequence is geometric and find the common ratio of the sequence.
3. For the geometric sequence find the exact value of the sixth term. Give your answer as a fraction.
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5#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Jeremy invests 8000 dollars into a savinog3a12 o+ wafogs account that pays an annual interest rate of 5.5 % , compoundoaawf 3o12o+ged annually.
1. Write down a formula which calculates that total value of the investment after n years.
2. Calculate the amount of money in the savings account after:
1. 1 year;
2. 3 years.
3. Jeremy wants to use the money to put down a $ 10000 deposit on an apartment. Determine if Jeremy will be able to do this within a 5 -year timeframe.
参考答案:    

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6#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Consider the infinite geometric sequence 4480,-3360,2520,nkc.hk/*vir ve :;b/p-1890, ...
1. Find the common ratio, r .   
2. Find the 20 th term.≈   
3. Find the exact sum of the infinite sequence.   

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7#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  $\text { The table shows the first four terms of three sequences: } u_{n}, v_{n} \text {, and } w_{n} \text {. }$



1. State which sequence is
$u_{n}$ is A $v_{n}$ is B $w_{n}$ is C

1. arithmetic; =  
2. geometric. =  
2. Find the sum of the first 50 terms of the arithmetic sequence.   
3 . Find the exact value of the 13 th term of the geometric sequence.   

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8#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An arithmetic sequence is given by 3,5k 9hmmu+hh4kiy ry tb.94*k* b,7, $\ldots $
1. Write down the value of the common difference, d .   
2. Find
1. $u_{10}$ ;   
2. $S_{10}$=   
3. Given that $u_{n}=253$ , find the value of n .   

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9#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Consider the infinite lxqcg .tdd +0m7k69 sqgeometric sequence 9000,-7200,5760,-4608, $\ldots $
1. Find the common ratio.   
2. Find the 25 th term.≈   
3. Find the exact sum of the infinite sequence.   

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10#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A tennis ball bounces on the grcuuh3)g3)cq2 hb4wm c ound n times. The heights of the bounces, $h_{1}, h_{2}, h_{3}, \ldots, h_{n}$ , form a geometric sequence. The height that the ball bounces the first time, $h_{1}$ , is 80 cm, and the second time, $h_{2}$ , is $60 \mathrm{~cm} $.
1. Find the value of the common ratio for the sequence.   
2. Find the height that the ball bounces the tenth time, $h_{10}$ .≈    cm
3. Find the total distance travelled by the ball during the first six bounces (up and down). Give your answer correct to 2 decimal places.≈    cm

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11#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The third term, $u_{3}$ , of an arithmetic sequence is 7 . The common difference of the sequence, d , is 3 .
1. Find $u_{1}$ , the first term of the sequence.   
2. Find $u_{60}$ , the 60 th term of sequence.

The first and fourth terms of this arithmetic sequence are the first two terms of a geometric sequence.   
3. Calculate the sixth term of the geometric sequence.≈   

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12#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The fifth term, $ u_{5}$ , of a geometric sequence is 125 . The sixth term, $u_{6}$ , is 156.25 .
1. Find the common ratio of the sequence. =   
2. Find $u_{1}$ , the first term of the sequence. =   
3. Calculate the sum of the first 12 terms of the sequence.≈   

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13#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The fourth term, $u_{4}$ , of a geometric sequence is 135 . The fifth term, $u_{5}$ , is 81 .
1. Find the common ratio of the sequence. =   
2. Find $u_{1}$ , the first term of the sequence. =   
3. Calculate the sum of the first 20 terms of the sequence.≈   

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14#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The fifth term, $u_{5}$ , of an arithmetic sequence is 25 . The eleventh term, $u_{11}$ , of the same sequence is 49 .
1. Find d , the common difference of the sequence.   
2. Find $u_{1}$ , the first term of the sequence.   
3. Find $S_{100}$ , the sum of the first 100 terms of the sequence.   

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15#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 3D printer builds a set of 49 Eiffel Tower Replicarif;y,w / -y:ai33nex .6)eczjbkderf )/wb xs in different sizes. The height of the l/kbiw z xfe3) )c aen6wde.3 r:j-y/irxfy;,bargest tower in this set is $ 64 \mathrm{~cm}$ . The heights of successive smaller towers are 95 % of the preceding larger tower, as shown in the diagram below.



1. Find the height of the smallest tower in this set.≈    cm
2. Find the total height if all 49 towers were placed one on top of another.≈    cm

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16#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Hannah buys a car for zl4vt ;f.6vcvzc18tx .8 k 9; jynzwbq $ 24900 . The value of the car depreciates by 16 % each year.
1. Find the value of the car after 10 years.

Patrick buys a car for 12000 dollars. The car depreciates by a fixed percentage each year, and after 6 years it is worth 6200 dollars . ≈   
2. Find the annual rate of depreciation of the car. ≈    %

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17#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Consider the following seqdp ui9o )8h7p5soep (ff2jam6uence of figures.


Figure 1 contains 6 line segments.
1. Given that Figure n contains 101 line segments, show that n=20 .
2. Find the total number of line segments in the first 20 figures. __
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18#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In an arithmetic sequence,8.npm 6zgi(xb $u_{5}=24$, $u_{13}=80$ .
1. Find the common difference.   
2. Find the first term.   
3. Find the sum of the first 20 terms in the sequence.   

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19#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The first three terms of a geometric sequence wgim2 ig9oi9 .ii61uiy2pv;l are $u_{1}=32$, $u_{2}=-16$,$ u_{3}=8$ .
1. Find the value of the common ratio, r .   
2. Find $u_{6}$ . =   
3. Find $S_{\infty}$ . =   

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20#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In an arithmetic sequence, qvp*/)uzf6wjf 1q)hzi --7nq vt3tg h$u_{4}=12$, $u_{11}=-9$ .
1. Find the common difference.   
2. Find the first term.   
3. Find the sum of the first 11 terms in the sequence.   

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21#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In an arithmetic sequence, the zs x1b2- w;zq1m/rjcc sum of the 2 nd and 6 th term is 32 .
Given that the sum of the first six terms is 120 , determine the first term and common difference of the sequence. $u_1$ =    d =   

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22#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In an arithmetic sequence, the sum of tj5 e-crt4m r-rhe 2 nd and 6 th term is 32 .
Given that the sum of the first six terms is 120 , determine the first term and common difference of the sequence.An arithmetic sequence has first term 45 and common difference -1.5 .
1. Given that the k th term of the sequence is zero, find the value of k .

Let $S_{n}$ denote the sum of the first n terms of the sequence.   
2. Find the maximum value of $S_{n}$ .   

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23#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
The Australian Koala Foundation estimatsg*g; jn yba1)g i:6d+vtg5twes that there are about 45000 koalas left in the wild in 2019 . A year before, in 2018 , the population of koalas was estimatat sg n1gt6;j+gvd:i*wg5 b)yed as 50000 . Assuming the population of koalas continues to decrease by the same percentage each year, find:
1. the exact population of koalas in 2022 ;
2. the number of years it will take for the koala population to reduce to half of its number in 2018 .
参考答案:    

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24#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Landmarks are placed along the road from Lond-sj5u x;st93b v8if(0ex b5pjhtmxh.on to Edinburgh and the distance between each landmark is ;j-ex83hu bs5 jtbf5ps 9.it( 0m hxxv16.1 $\mathrm{~km}$ . The first landmark placed on the road is 124.7 $\mathrm{~km}$ from London, and the last landmark is near Edinburgh. The length of the road from London to Edinburgh is 667.1 $\mathrm{~km} $.
1. Find the distance between the fifth landmark and London.   
2. Determine how many landmarks there are along the road.   

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25#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
The first term of an arithmetic sequence is 24 and the common differe)t 2aghmn r*4pnce is 16 . mht2g)n4*a pr
1. Find the value of the 62 nd term of the sequence.

The first term of a geometric sequence is 8 . The 4 th term of the geometric sequence is equal to the 13 th term of the arithmetic sequence given above. __
2. Write down an equation using this information. __
3. Calculate the common ratio of the geometric sequence. __
参考答案:    

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26#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  On 1st of January 2021, Fiona decides to take out a bank loan to purchase a n2si (26n; ubgp6bswky ej f/ofu,va72ew Tesla electric car. Fiona takes out a loan of P dollars with a bank that offers a nominal annual interest rate of 2.ons 2vjy(f wgeup 7s f2/ a2k,;bub6i66 % , compounded monthly.
The size of Fiona's loan at the end of each year follows a geometric sequence with common ratio, $\alpha$ .
1. Find the value of $\alpha$ , giving your answer to five significant figures.

The bank lets the size of Fiona's loan increase until it becomes triple the size of the original loan. Once this happens, the bank demands that Fiona pays the entire amount back to close the loan.≈   
2. Find the year during which Fiona will need to pay back the loan.   

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27#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  On Gary's 50 th birthday, he invests P dollars in an account thlwugs gs.1ubz1 2ukhh3 x7y10 at pays a nominal annual interest rate of 5 % , compounded monthlyzhubs11x1h g 3 y.2s 07ulgkwu. The amount of money in Gary's account at the end of each year follows a geometric sequence with common ratio, $\alpha$ .
1. Find the value of $\alpha$ , giving your answer to four significant figures.

Gary makes no further deposits or withdrawals from the account.≈   
2. Find the age Gary will be when the amount of money in his account will be double the amount he invested.   

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28#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In an arithmetic sequence, the third fj t2q(rj/5hzm 3iycjw we:6-6)jlkoterm is 41 and the ninth term is 23 .
1. Find the common difference.   
2. Find the first term.   
3. Find the smallest value of n such that $S_{n}<0$ .   

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29#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The first three terms of a ge-3,ul bube-ntt fg44vy a7 g+pometric sequence are $ u_{1}=0.8, u_{2}=2.4, u_{3}=7.2 $.
1. Find the value of the common ratio, r .   
2. Find the value of $S_{8}$ .   
3. Find the least value of n such that $S_{n}>35000$ .   

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30#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The first three terms of a geometric sequkrv0 d7p9 ha5cw,sy-pence are $u_{1}=0.4, u_{2}=0.6, u_{3}=0.9$a .
1. Find the value of the common ratio, r .≈    !num!2%
2. Find the sum of the first ten terms in the sequence.   
3. Find the greatest value of n such that $S_{n}<650$ .   

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31#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In a geometric sequence, ox0w1jx 53 tfp$u_{2}=6, u_{5}=20.25$ .
1. Find the common ratio, r .   
2. Find $u_{1}$ .   
3. Find the greatest value of n such that $u_{n}<200$ .   

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32#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In this question give3u 0tv w,x( a/udab3qv all answers correct to the nearest whole number.
A population of goats on an island starts at 232 . The population is expected to increase by 15 \% each year.
1. Find the expected population size after:
1. 10 years;≈   
2. 20 years.≈   
2. Find the number of years it will take for the population to reach 15000 .   

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33#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Maria invests $ 25000 into a savings account that pays a nominal annual interest rate of 4.25 % , compounded monthly.
1. Calculate the amount of money in the savings account after 3 years.
2. Calculate the number of years it takes for the account to reach 40000 dollars.
参考答案:    

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34#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Greg has saved 2000 British pouj.tt j y)z6zn(nds (GBP) over the last six months. He decided to deposit his savings in a bank which offers a nominal annual interest rate of 8 % , compounded y tzj(zj)tn. 6monthly, for two years.
1. Calculate the total amount of interest Greg would earn over the two years. Give your answer correct to two decimal places.

Greg would earn the same amount of interest, compounded semi-annually, for two years if he deposits his savings in a second bank.   
2. Calculate the nominal annual interest rate the second bank offers.≈   

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35#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Emily deposits 2000 Australian dollars (AUD) into a bank acutt3c 6lcusc46)- imu iws.q(count. The bank pays a nominal annual interest rate of 4 % , compoundedt6 cic-miscq u l).3su4w(t u6 monthly.
1. Find the amount of money that Emily will have in her bank account after 5 years. Give your answer correct to two decimal places.

Emily will withdraw the money back from her bank account when the amount reaches 3000 AUD.
2. Find the time, in months, until Emily withdraws the money from her bank account.
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36#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In this question give:;frorbc t;/ 4f8 wnkau-yy/ y all answers correct to two decimal places.
Mia deposits 4000 Australian dollars (AUD) into a bank account. The bank pays a nominal annual interest rate of 6 % , compounded semi-annually.
1. Find the amount of interest that Mia will earn over the next 2.5 years.

Ella also deposits AUD into a bank account. Her bank pays a nominal annual interest rate of 4 % , compounded monthly. In 2.5 years, the total amount in Ella's account will be 4000 AUD.≈   
2. Find the amount that Ella deposits in the bank account.≈   

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37#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Julia wants to buy a house that 9w.uw ,h4ccq /y(*iff5ae mpbrequires a deposit of 74000 Australian dollars (AUD)ycq .p9*we ucf5(bhfw, 4a/mi.
Julia is going to invest an amount of AUD in an account that pays a nominal annual interest rate of 5.5 % , compounded monthly.
1. Find the amount of AUD Julia needs to invest to reach 74000 AUD after 8 years. Give your answer correct to the nearest dollar.

Julia's parents offer to add 5000 AUD to her initial investment from part (a), however, only if she invests her money in a more reliable bank that pays a nominal annual interest rate only of 3.5 % , compounded quarterly. ≈   
2. Find the number of years it would take Julia to save the 74000 AUD if she accepts her parents money and follows their advice. Give your answer correct to the nearest year.   

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38#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Ali bought a car forjq:.nbzn6 h:i $ 18000 . The value of the car depreciates by 10.5 % each year.
1. Find the value of the car at the end of the first year.≈   
2. Find the value of the car after 4 years.≈   
3. Calculate the number of years it will take for the car to be worth exactly half its original value. ≈   

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39#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  On 1st of January 2022 , Grace invests P dollars in an account t9p5 mn zoymrn2n1cftg*z:k40hat pays a nominal annual interest rate of 6 % , compounded quarterly. The amount of money in Grace's account at the end of each year follows a geometric sequence witr9n*1cgyonzz0n:m pf2k4m5 th common ratio, $\alpha$ .
1. Find the value of $\alpha$ , giving your answer to four significant figures.

Grace makes no further deposits or withdrawals from the account.≈   
2. Find the year in which the amount of money in Grace's account will become triple the amount she invested.    years

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40#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Let $u_{n}=5 n-1$ , for $n \in \mathbb{Z}^{+}$ .
1. 1. Using sigma notation, write down an expression for $u_{1}+u_{2}+u_{3}+\cdots+u_{10}$ .
2. Find the value of the sum from part (a) (i).

A geometric sequence is defined by $v_{n}=5 \times 2^{n-1}$ , for $n \in \mathbb{Z}^{+}$ .
2. Find the value of the sum of the geometric series $\sum_{k=1}^{6} v_{k}$ .
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41#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Peter is playing on a swing duri,;+*nyjyz0 sy :q )6hesk qtgu-z0x lpng a school lunch break. The height of the first swing was y,-jsn6gqzqy0:; 0ys xzkpe h)tul+* 2 $\mathrm{~m}$ and every subsequent swing was 84 % of the previous one. Peter's friend, Ronald, gives him a push whenever the height falls below $1 \mathrm{~m}$ .
1. Find the height of the third swing.≈   
2. Find the number of swings before Ronald gives Peter a push. n =   
3. Calculate the total height of swings if Peter is left to swing until coming to rest.   

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42#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Sarah walks to school each morning. During thea4zgpw-g jc.a.u.a e1 first minute, she travels 130 metres. In each subsequent minute, she travels 5 metres less than the distance she travelled during the previous minute. The distance from her home to school is 950 metres. Sarah leaves her house at 8: 00 am and must be at school by 8: 10 am. Will Sarah arrive to school on time? jaup w-4ce1g. a..gz aJustify your answer.
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43#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Jack rides his bike to work each morning. During the first mi.3t eily1xnwf/i 0j,tnute, he travels 160 metres. In each subsequent minute, he travels 80 % of the distance travelled during the previous minute. The distance from his home to work is 750 metres. Jack leaves his house at 8y0 etlix/ tn.i13f j,w:30 am and must be at work at 8:40 am. Will Jack arrive to work on time? Justify your answer.
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44#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The third term of an arithmetic sequence is :m s.y .lgbq38 yoom1oequal to 7 and the sum of the first 8 terms is 20 . Find the common difference and the firs.om 1.s8lqybo3:ogymt term.   

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45#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The first term and the common ratio of a geometric series are dtv;jjom 5, ,ceenoted, respectivvt,j,c e5 o;mjely, by $u_{1}$ and r , where $u_{1}$, $r \in \mathbb{Q}$ . Given that the fourth term is 64 and the sum to infinity is 625 , find the value of $u_{1}$ and the value of r .$u_{1}$ =    r =   

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46#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The seventh term of an arithmetic sequence n c37spkl4brnd4g 1g;ua u+*uis equal to 1 and the sum of the first 16 terms is 52 . nr d+41 uls*;abu7gugn3kcp 4 Find the common difference and the first term. $u_1$ =   

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47#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  $\text { The sum of an infinite geometric sequence is } 27 \text {. The second term of the sequence is } 6 \text {. Find the possible values of } r \text {. }$      

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48#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  $\text { The sum of the first three terms of a geometric sequence is } 92.5 \text {, and the sum of the infinite sequence is } 160 \text {. Find the common ratio. }$   

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49#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The 1st, 5 th and 13 th ternxj)e0p6xuw os5j0 (nms of an arithmetic sequence, with common difference jpw05xu xn60 n)seo j(d, $d \neq 0$ , are the first three terms of a geometric sequence, with common ratio r, $r \neq 1$ . Given that the 1 st term of both sequences is 12 , find the value of d and the value of r . r =    d =   

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50#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  $\text { The sum of the first three terms of a geometric sequence is } 81.3 \text {, and the sum of the infinite sequence is } 300 \text {. Find the common ratio. }$   

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51#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  It is known that the numx*m*m*r g4 / neds;ru/ 7mmndwber of trees in a small forest will decrease by 5 % each year unless some new trees are planted. At the end of each year, 600 new trees are planted to the forest At the stnx/ 7/wur*mgds*e m; mm4*nrdart of 2021 , there are 8200 trees in the forest.
1. Show that there will be roughly 9060 trees in the forest at the start of 2026 . ≈   
2. Find the approximate number of trees in the forest at the start of 2041 .≈   

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52#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  $\text { 1. The following diagram shows }[\mathrm{PQ}] \text {, with length } 4 \mathrm{~cm} \text {. The line is divided into an infinite number of line segments. The diagram shows the first four segments. }$




$\text { 1. The following diagram shows }[\mathrm{PQ}] \text {, with length } 4 \mathrm{~cm} \text {. The line is divided into an infinite number of line segments. The diagram shows the first four segments. }$The length of the line segments are m $\mathrm{~cm}$, $m^{2} \mathrm{~cm}, m^{3} \mathrm{~cm}, \ldots ,$ where $0\lt n \lt1$ .
Show that $m=\frac{4}{5}$ .   
2. The following diagram shows [RS], with length l $\mathrm{~cm}$ , where l$\gt $1 . Squares with side lengths $n \mathrm{~cm}, n^{2} \mathrm{~cm}, n^{3} \mathrm{~cm}, \ldots$ , where $0\lt n \lt1$ , are drawn along [RS]. This process is carried on indefinitely. The diagram shows the first four squares.


$\text { The total sum of the areas of all the squares is } \frac{25}{11} \text {. Find the value of } l \text {. }$   

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53#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
The first three terms of an infinite geometric sequence are k-4,4, k+2 , where0fo +ylm( /9a0beo y uvgznipvv7+2r0 vomilo 72 n90rbev ypzgv (0f/ +0yua+ $k \in \mathbb{Z}$ .
1. 1. Write down an expression for the common ratio, r .
2. Hence show that k satisfies the equation $k^{2}-2 k-24=0$ .
2. 1. Find the possible values for k .
2. Find the possible values for r .
3. The geometric sequence has an infinite sum.
1. Which value of r leads to this sum. Justify your answer.
2. Find the sum of the sequence.
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54#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Let $f(x)=e^{3 \sin \left(\frac{\pi x}{4}\right)}$ , for x>0 .
The k th maximum point on the graph of f has x -coordinate $x_{k}$ , where k $\in \mathbb{Z}^{+}$ .
1. Given that $x_{k+1}=x_{k}+d$ , find d .   
2. Hence find the value of n such that $\sum_{k=1}^{n} x_{k}=992$ .   

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55#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Alex and Julie each have a goal ob+,gxnuky 1 5hf saving 30000 dollars to put towards a house deposit. They each have 16000 dollars to invest+h5nbg,u1xy k.
1. Alex chooses his local bank and invests his 16000 dollars in a savings account that offers an interest rate of 5 % per annum compounded annually.
1. Find the value of Alex's investment after 7 years, to the nearest hundred dollars.
2. Alex reaches his goal after n years, where n is an integer. Determine the value of n .
2. Julie chooses a different bank and invests her 16000 dollars in a savings account that offers an interest rate of r % per annum compounded monthly, where r is set to two decimal places.
Find the minimum value of r needed for Julie to reach her goal after 10 years.
3. Xavier also wants to reach a savings goal of 30000 dollars. He doesn't trust his local bank so he decides to put his money into a safety deposit box where it does not earn any interest. His system is to add more money into the safety deposit box each year. Each year he will add one third of the amount he added in the previous year.
1. Show that Xavier will never reach his goal if his initial deposit into the safety deposit box is 16000 dollars.
2. Find the amount Xavier needs to initially deposit in order to reach his goal after 7 years. Give your answer to the nearest dollar.
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56#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Grant wants to save 40000 dollars over 5 years to help his son . k:.qrm37y zi09p + bdmywlljpay for his college tuition. He deposits 20000 dolla3lri9zmp.kw mj q yl+: d.70ybrs into a savings account that has an interest rate of 6 % per annum compounded monthly for 5 years.
1. Show that Grant will not be able to reach his target.
2. Find the minimum amount, to the nearest dollar, that Grant would need to deposit initially for him to reach his target.

Grant only has 20000 dollars to invest, so he asks his sister, Caroline, to help him accelerate the saving process. Caroline is happy to help and offers to contribute part of her income each year. Her annual income is 37500 dollars per year. She starts by contributing one fifth of her annual income, and then decreases her contributions by half each year until the target is reached. Caroline's contributions do not yield any interest.
3. Show that Grant and Caroline together can reach the target in 5 years.

Grant and Caroline agree that Caroline should stop contributing once she contributes enough to complement the deficit of Grant's investment.
4. Find the whole number of years after which Caroline will will stop contributing.
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57#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
The first three terms of an infinite sequence, in order, are jdwwem zp6a9;,*k- d k3vuqe 7t8lp:o$2 \ln x, q \ln x, \ln \sqrt{x}$ where x>0 .
First consider the case in which the series is geometric.
1. 1. Find the possible values of q .
2. Hence or otherwise, show that the series is convergent.
2. Given that q>0 and $ S_{\infty}=8 \ln 3$ , find the value of x .

Now suppose that the series is arithmetic.
3. 1. Show that $q=\frac{5}{4}$ .
2. Write down the common difference in the form $m \ln x$ , where $m \in \mathbb{Q}$ .
4. Given that the sum of the first n terms of the sequence is $\ln \sqrt{x^{5}}$ , find the value of n .
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58#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The sides of a square z-: exrij2 )ub*4d krvare 8 $\mathrm{~cm}$ long. A new square is formed by joining the midpoints of the adjacent sides and two of the resulting triangles are shaded as shown. This process is repeated 5 more times to form the right hand diagram below.




1. Find the total area of the shaded region in the right hand diagram above.≈   
2. Find the total area of the shaded region if the process is repeated indefinitely.≈   

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59#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
The first two terms of an infinite geometric sequence, in order, /v9l98gywrb:pbbec g6-asf3are

$3 \log _{3} x, 2 \log _{3} x, \text { where } x>0 \text {. }$

1. Find the common ratio, r .
2. Show that the sum of the infinite sequence is $9 \log _{3} x$ .

The first three terms of an arithmetic sequence, in order, are

$\log _{3} x, \log _{3} \frac{x}{3}, \log _{3} \frac{x}{9}, \text { where } x>0$ .

3. Find the common difference d , giving your answer as an integer.

Let S_{6} be the sum of the first 6 terms of the arithmetic sequence. __
4. Show that $S_{6}=6 \log _{3} x-15$
5. Given that $S_{6}$ is equal to one third of the sum of the infinite geometric sequence, find x , giving your answer in the form $a^{p}$ where a, $p \in \mathbb{Z}$ .
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60#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Given a sequence of integers, between 20 and 300x1qcio +7k y3jtsq(iq:yri0o,jy3 a5 , which are divisible by 9 .
1. Find their sum.
2. Express this sum using sigma notation.

An arithmetic sequence has first term -500 and common difference of 8 . The sum of the first n terms of this sequence is negative.
3. Find the greatest value of n .
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61#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The first three terms of a geometric sequence are xwju7-2w n 6*tipnv o5$\ln x^{9}, \ln x^{3}, \ln x$ , for x>0 .
1. Find the common ratio.   
2. Solve $\sum_{k=1}^{\infty} 3^{3-k} \ln x=27$ . $a^b$ a =    b =   

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62#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
The first two terms kj7/of y 0(kttt6mz:kof an infinite geometric sequence are $u_{1}=20$ and $u_{2}=16 \sin ^{2} \theta$ , where $0<\theta<2 \pi$ , and $\theta \neq \pi$ .
1. 1. Find an expression for r in terms of $\theta$ .
2. Find the possible values of r .
2. Show that the sum of the infinite sequence is $\frac{100}{3+2 \cos 2 \theta}$ .
3. Find the values of $\theta$ which give the greatest value of the sum.
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63#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Bill takes out a bank loan ogzanx5p((3b2 g7u dk z+wf od6f 100000 dollars to buy a premium electric car, at an annual interest rate of 5.49 % . The bodxnz5(7( fu 3pazgg2wkd+ 6interest is calculated at the end of each year and added to the amount outstanding.
1. Find the amount of money Bill would owe the bank after 10 years. Give your answer to the nearest dollar.

To pay off the loan, Bill makes quarterly deposits of P dollars at the end of every quarter in a savings account, paying a nominal annual interest rate of 3.2 % . He makes his first deposit at the end of the first quarter after taking out the loan.
2. Show that the total value of Bill's savings after 10 years is $P\left[\frac{1.008^{40}-1}{1.008-1}\right]$ .
3. Given that Bill's aim is to own the electric car after 10 years, find the value for P to the nearest dollar.

Melinda visits a different bank and makes a single deposit of Q dollars, the annual interest rate being 3.5 % .
4. 1. Melinda wishes to withdraw 8000 dollars at the end of each year for a period of n years. Show that an expression for the minimum value of Q is

$\frac{8000}{1.035}+\frac{8000}{1.035^{2}}+\frac{8000}{1.035^{3}}+\cdots+\frac{8000}{1.035^{n}}$ .

2. Hence, or otherwise, find the minimum value of Q that would permit Melinda to withdraw annual amounts of 8000 dollars indefinitely. Give your answer to the nearest dollar.
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64#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
This question asks you to invea8u7efd510 byhw qn.d stigate some properties of hexagonal numbers.
Hexagonal numbers can be represented by dots as shown below where $h_{n}$ denotes the n th hexagonal number, $n \in \mathbb{N}$ .


Note that 6 points are required to create the regular hexagon $h_{2}$ with side of length 1 , while 15 points are required to create the next hexagon $h_{3}$ with side of length 2 , and so on.
1. Write down the value of $h_{5}$ .
2. By examining the pattern, show that $ h_{n+1}=h_{n}+4 n+1, n \in \mathbb{N} $.
3. By expressing $h_{n}$ as a series, show that $h_{n}=2 n^{2}-n, n \in \mathbb{N}$ .
4. Hence, determine whether 2016 is a hexagonal number.
5. Find the least hexagonal number which is greater than 80000 .
6. Consider the statement:
45 is the only hexagonal number which is divisible by 9 .
Show that this statement is false.

Matt claims that given $h_{1}=1 $ and $h_{n+1}=h_{n}+4 n+1, n \in \mathbb{N}$ , then

$h_{n}=2 n^{2}-n, \quad n \in \mathbb{N}$

7. Show, by mathematical induction, that Matt's claim is true for all $ n \in \mathbb{N}$ .
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65#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
The cubic polynomial vmx r tn67w)up+t6xb3k-dnk, equation $x^{3}+b x^{2}+c x+d=0$ has three roots $x_{1}$, $x_{2}$ and $x_{3}$ . By expanding the product $\left(x-x_{1}\right)\left(x-x_{2}\right)\left(x-x_{3}\right) $, show that
1. 1. $ b=-\left(x_{1}+x_{2}+x_{3}\right)$ ;
2. $c=x_{1} x_{2}+x_{1} x_{3}+x_{2} x_{3}$ ;
3. $d=-x_{1} x_{2} x_{3}$ .

It is given that b=-9 and c=45 for parts (b) and (c) below.
2. 1. In the case that the three roots $x_{1}$, $x_{2}$ and $x_{3}$ form an arithmetic sequence, show that one of the roots is 3 .
2. Hence determine the value of d .
3. In another case the three roots form a geometric sequence. Determine the value of d .
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