Answer
$3$
Work Step by Step
We need to find the limit for $\lim\limits_{(x,y) \to (1,1)} \dfrac{x^3-y^3}{xy-1}$
or, $\lim\limits_{(x,y) \to (1,1)} \dfrac{(x-y) [(xy)^2+xy+1]}{(xy-1)}=\lim\limits_{(x,y) \to (1,1)} x^2+xy+1$
Thus, $1+(1)(1)+1=3$