Write an equation for the tangent plane?

Question

If f(0, -2)=4 and gradient f(0, -2)=<4/5, 12/25>, write an equation for the tangent plane to the surface z=f(x, y) at this point.

Answer 1

F(x, y, z) = f(x, y) - z

Fx = fx = 4/5

Fy = fy = 12/25

Fz = -1

So, the equation for the tangent plane is (4/5)x + (12/25)(y+2) - (z-4) = 0