Question

Identify a1 and r for the geometric sequence an= -256(-1/4) n-1

Answer 1

Answer:

a1=-256

r= -1/4

Approximated the sum of the first 17 terms to the nearest tenth. Sum= -204.8

Step-by-step explanation:

Answer 2

Answer:  $a_1=-256$

$r=-\frac{1}{4}$

Step-by-step explanation:

The geometric sequence is given by :-

$a,ar,ar^2,ar^3,.....$, where a is the first term and r is the constant ratio.

The given explicit formula of nth term :-$a_n=-256(-\frac{1}{4})^{n-1}$

First term=$a_1=-256(-\frac{1}{4})^{1-1}=-256(1)=-256$

Hence, $a_1=-256$

Second term = $a_2=-256(\frac{1}{4})^{2-1}=-256(-\frac{1}{4})=64$

Now, $r=\frac{a_2}{a_1}=\frac{64}{-256}=-\frac{1}{4}$

hence,  $r=-\frac{1}{4}$