Answer
$\dfrac{x^3}{1-x} ; |x| \lt 1 $
Work Step by Step
Recall the Taylor series for $\dfrac{1}{1-x}= 1+x+x^2+......+x^n+.....; |x| \lt 1$
or, $=x^3+x^4+x^5+x^6+x^7+.....$
or, $=x^3(1+1+1+1+1....)$
or, $=x^3 (\dfrac{1}{1-x})$
or, $=\dfrac{x^3}{1-x} ; |x| \lt 1 $