Question

Find the indicated term of the geometric sequence. a8 for 4, -12, 36, ...

Answer 1

Answer:

The 8th term of geometric sequence is -8748

ie., $a_{8}=-8748$

Step-by-step explanation:

Given geometric sequence is 4,-12,36,...

Geometric sequence can be written as

$a_{1},a_{2},a_{3},..,$

$a_{1}=4=a$

$a_{2}=-12=ar$

$a_{3}=36=ar^2$

and so on.

common ratio is $r=\frac{a_{2}}{a_{1}}$

$r=\frac{-12}{4}$

$r=-3$

$r=\frac{a_{3}}{a_{2}}$

$r=\frac{36}{-12}$

$r=-3$

Therefore $r=-3$

Geometric sequence of nth term is $a_{n}=ar^{n-1}$

To find the 8th term:

$a_{8}=ar^{8-1}$

$a_{8}=ar^{7}$

here a=4 and r=-3

$a_{8}=ar^{7}$

$=4\times (-3)^7$

$=4\times (-2187)$

$=-8748$

$a_{8}=-8748$

Therefore the 8th term of geometric sequence is -8748

Answer 2

Answer:

76

Step-by-step explanation: