Please help with practice problems 1, 2, and 3.

1.

Let f (x, y) = ewx'y). Find the equation for the tangent plane to the graph of f at the point (1, 2) . (U se symbolic notation and fractions where needed.) Find the equation of the tangent plane to the graph of f(x,y) =1n(16x2 13)?) at the point (1, 1). (Use symbolic notation and fractions where needed. Enter your answer using x-, y, z-coordinates.) the equation: I | Find the equation of the tangent plane to the graph of G(u, w) = - cos (uw) at the point (5, (Use symbolic notation and fractions where needed. Enter your answer using u-, w-, z-coordinates.) the equation