Question

Find the fifthterm in the geometricsequence, given the first term and the common ratioa1 = 5 and r = -3a5=?

Answer 1

Given: A geometric sequence with first term and the common ratio a1 = 5 and r = -3.

Required: Fifth term of the geometric series.

Explanation:

In a geometric sequence, with first term 'a' and common ratio 'r'

nth term is

$a_n=ar^{n-1}$

So the fifth term is

$a_5=ar^4$

a = 5 and r = - 3.

So

$\begin{gathered} a_5=(5)(-3^)^4 \\ a_5=5(81) \end{gathered}$

So

$a_5=405$

Final Answer: The fifth term of Geometric sequence is 405.