Question

Find s8 for the following geometric sequence: 3, –6, 12, –24.

Answer 1

Answer:

 $S_{8}$ = $-255)$.

Step-by-step explanation:

Given  :  geometric sequence: 3, –6, 12, –24.

To find : Find s8 for the following geometric .

Solution : We have given geometric sequence: 3, –6, 12, –24.

Where, first term = 3, common ration : $\frac{-6}{3}$ = -2.

Formula used  :  $a(\frac{1-r^{n}}{1-r} )$

Where, a = first term , r = common ratio.

$S_{8}$ = $3(\frac{1-(-2)^{8}}{1-(-2)} )$.

$S_{8}$ = $3(\frac{1- 256}{1+2} )$.

$S_{8}$ = $3(\frac{-255}{3} )$.

$S_{8}$ = $3 * (85)$.

$S_{8}$ = $-255)$.

Therefore, $S_{8}$ = $-255)$.

Answer 2

Find s8 for the following geometric sequence: 3, –6, 12, –24. = –255