topic badge

8.04 Geometric sequences

Interactive practice questions

$\$3900$$3900 is invested for three years at a rate of $10%$10% per annum, compounding annually.

a

Complete the recurrence relation for this situation.

$t_{n+1}$tn+1$=$=$\editable{}$$t_n$tn, where $t_0$t0$=$=$\editable{}$.

b

Use the sequence facility of your calculator to complete the table below to determine the final value of the investment.

  Balance + interest Total balance Interest earned
First year $-$ $\$3900$$3900 $\$390$$390
Second year $\$3900+\$390$$3900+$390 $\$4290$$4290 $\$429$$429
Third year $\$4290+\$$$4290+$$\editable{}$ $\$$$$\editable{}$ $\$$$$\editable{}$
Fourth year $\$4719$$4719$+$+$\$$$$\editable{}$ $\$$$$\editable{}$ $-$
c

Calculate the total interest earned over the three years.

Medium
2min

$\$8000$$8000 is invested at $6%$6% p.a., compounded annually.

Medium
3min

Callum invests $\$5700$$5700 into an investment account that pays $3.2%$3.2% per annum, compounded annually.

Medium
2min

Erica invests $\$50000$$50000 into an investment account that pays $2.8%$2.8% per annum, compounded annually.

Medium
2min
Sign up to access Practice Questions
Get full access to our content with a Mathspace account

Outcomes

2.2.5

recognise and use the recursive definition of a geometric sequence:t_n+1=t_n r

2.2.6

develop and use the formula t_n=t_1*r^(n−1) for the general term of a geometric sequence and recognise its exponential nature

2.2.7

understand the limiting behaviour as n→∞ of the terms t_n in a geometric sequence and its dependence on the value of the common ratio r

2.2.9

use geometric sequences in contexts involving geometric growth or decay, such as compound interest

What is Mathspace

About Mathspace