3) In the following problems, use the chain rule to find the derivative of fog at the given point a. a ) f ( x , y , z ) = ( xyz, x2 + yz), g(x) = (x, 2x, 3x) at a= 1. b ) f ( x, y ) = ( xy, x2 - y, y? ) , g ( x, y, z) = ( zy? , y= = z) at a = ( 1, 0, 2)