please Help, Hand writing is perfered.

1. Find the second partial derivativesf(x, y) = y* - 4xy3 az 2. Use implicit differentiation to find 8x + 8y2 4z2 = 2x(y +z). 3. Find the local maximum and minimum value and saddle points of the function f(x,y) = x2 - xy + y2 - 9x + 6y + 9 4. Find the limit lim xycos(x - 2y) (xy)-(10,5) 5. Find fyx for the function f(x,y) = 4xy - 7xy? 6. Use the Chain rule to find us where s=4,t=0, w = x2 + y2 + z2 x=st, y=s cost, z=s sint. 7. Find three positive numbers whose sum is 400 and whose product is a maximum. 8. Use Lagrange's multiplies to find the maximum value of the function subject to the given constraints f(x, y, z)=x+2y, x+y+z= 1, y2 + z2 = 1. 9. Find the equations for the tangent plane and the normal line to the surface with equation x2 +9y2 + 9z2 = 22 at the point P(2, 1, 1). aw S