Question

how do i find the value of the infinite series for x in the interval -1 15 years ago

Answer 1

Can someone help please??

Answer 2

We know that sum ((x^n),n,0,infinity) = 1/(1-x), so

sum(2(-1^n)(x^n),n,0,infinity)
= 2 sum((-1^n)(x^n),n,0,infinity)
= 2 sum((-x)^n,n,0,infinity)
= 2 [1/(1-(-x))]
= 2/(1+x)