Question 3
Figure out the following limits.
(1) $\lim_{(x,y)\to(-2,1)} \frac{x^2 - 2x - y^2 + 2y}{x^2 - 2x + y^2 + 2y}$
(2) $\lim_{(x,y)\to(0,0)} xy^2 \sin(\frac{1}{x^2 + y^2})$
(3) $\lim_{(x,y)\to(\pi/2,\pi/2)} \frac{\cos(y) - \sin(2y)}{\cos(x)\cos(y)}$
