Calculate-absolute minimum and maximum

Question

Problem:

Absolute minimum and maximum

1.)f(x,y)= 2x^3 + y^4, D={(x,y), x^2 + y^2 less than or equal to 1}

2.)f(x,y)= x^3 - 3x - y^3 + 12y, D is the quadrilateral whose vertices are (-2,3), (2,3), (2,2), and (-2,-2).