I need help with all 3

9 x+4y 3. Find an equation for the tangent plane to the surface at the point Po(l,2). b. Find parametric equations for the normal line to the surface through the same point as in part b. 1. For the surface: : = 2. Suppose that over a certain region of space the electrical potential, i". is given by l'(.r,_}-'.:) = 5x: - 313' + xv: a. Find the rate of change of the potential at the point (3 4 S) in the direction of I? = i' + j k b. In which direction does I' change most rapidly at that point? c. What is the maximum rate of change at that point? 3. Evaluate by changing the order of integration. 3'10]; xzm d3\" b II 113? )drd}21rsin(rr.3r