Each of these extreme value problems has a solution with both a maximum value and a minimum value. Use Lagrange multipliers to find the extreme values of the function subject to the given constraint.

1) f(x,y)=x^2y , x^2+y^2=5

2) f(x,y)=x^2+y^2+z^2 , x^2+y^2+z2+xy=12