Question

8,40,200,...t10find the 4th term

Answer 1

SOLUTION

We are asked to find the 4th term of the series above

The first term a = 8,

This is a geometric series because

The common ratio r is 5,

That is

$\begin{gathered} \frac{200}{40}=5 \\ \frac{40}{8}=5 \end{gathered}$

nth term of a geometric series is given by the formula

$T_n=ar^{n-1}$

The 4th term becomes

$\begin{gathered} T_n=ar^{n-1} \\ T_4=ar^{4-1} \\ T_4=ar^3 \\ T_4=8\times5^3 \\ T_4=8\times125 \\ T_4=1000 \end{gathered}$

Hence the 4th term is 1,000