Find the derivative of the function at Po in the direction of A. f(x, y,z) = 3 e cos (yz), Po(0,0,0), A=2i+ 4j + 2k (DAf) (0,0,0) = (Type an exact answer, using radicals as needed.)If the equation F(x,y,z) =0 determines z as a differentiable function of x and y, then, at the points where F #0, the following equations are true. dz FX Fy and F . ay F . Use these equations to find the values of dz / dx and oz / dy at the given point. 3z" - 5xy + 3yz + 3y" - 83 =0, (4,2,3) . . . = (Type an integer or a simplified fraction.) ox (4,2,3 )