Answer
$\dfrac{9}{4}$
Work Step by Step
Formula to calculate the sum of the infinite terms of a geometric sequence is: $s_n=\dfrac{a_1}{(1-r)}$
Here, $r=\dfrac{a_2}{a_1}=\dfrac{-1}{3}$
As we are given that, $n=\infty$
Thus, $s_{\infty}=\dfrac{3}{(1-(-\dfrac{1}{3}))}$
or, $s_{\infty}=\dfrac{9}{4}$