Question

please help me solve this equation

Answer 1

Answer:

-85

Step-by-step explanation:

We are given the equation $E^8_{n=1}$$(-2)^{n-1}$ and are asked to evaluate it.

This can be solved using the geometric sequence, but first we have to determine our "r", "n", and $a_{1}$.

Of course $a_{1}$ is equal to 1. Therefore,

$a_{1$ = 1

$r=$

$n=$

(-2) is the change per number in the sequence, therefore -2 is our "r".

$a_{1$ = 1

$r=-2$

$n=$

The number "8" on $E^8_{n-1}$ represents the "n". Therefore 8 is our "n".

$a_{1}=1$

$r=-2$

$n=8$

Use the geometric sequence sum formula and substitute :

$a_{1} \frac{1-r^n}{1-r}$

$1* \frac{1-(-2)^8}{1-(-2)}$

$1* \frac{1-(-2)^8}{1+2}$

$1* \frac{1-256}{1+2}$

$1* \frac{-255}{3}$

$1 * -85$

$-85$