I need some help with these questions. Thank you so much for your help in advance

1) Find the absolute minimum and maximum value for the function f(x,y) =xy+x3+2x2 on the region R = [ (x,y) : -2 x2,0y4x2 ]

2) Use the chain rule to find dw/dt for z =lnx2+y2+z2 where x(t) = sin t, y(t) = cos t, and z(t) = tan(t)

3) Use Lagrange multipliers to find the extreme values of the function f(x,y) =exy subject to the constraintx3+y3=16