kill(all)$

van=facebook.com/LearningCalculus$

f(x,y):=(2*x)^2*y^2-2^(x+y^2)-32;

solve(f(x,y),y);

limit(-sqrt(2^(y^2+x)+32)/(2*x),x,-inf);

limit( sqrt(2^(y^2+x)+32)/(2*x),x,-inf);

f(4,1);

f(4,-1);