1. Define partial derivative of f(x, y). Compute f(x,y) f(x,y) f(x,y) f (x,y) f(x,y) f(x,y), xy fxx (x,y), fx (x,y), fx (x,y), fx (x,y), f (x, y) of the following functions: - - 2 (i) f(x,y) = x + y (ii) f(x, y) = xy + xy (iii)/(x, y) = x* sin(xy ) (x, y) + (0,0) (x, y)=(0,0)