Intermediate Algebra for College Students (7th Edition)

$\dfrac{2}{3}$
Formula to calculate the sum of the infinite terms of a geometric sequence is: $s_n=\dfrac{a_1}{(1-r)}$ Here, $r=\dfrac{a_2}{a_1}=\dfrac{-1}{2}$ As we are given that, $n=\infty$ Thus, $s_{\infty}=\dfrac{1}{(1-(-\dfrac{1}{2}))}$ or, $s_{\infty}=\dfrac{2}{3}$