1. Let f (x, y, z) = xy sinz - yz. Find fx, fy, fz. 2. f ( x, y , z ) = x y z+ sinxy. Find of of of arf arf arf d's (you will need to use the ox dy ' Oz, ax2 ' dy2 ' azz ' axdy product rule in the last part) aw 2 2 w Ow Ow 3. For w= x' - y' - 2xy +6, find and at the points where E ax 2 = 0 Hint: you will Ox ay Ow ow need to solve two simultaneous equations for E 0, find two pairs of values for y and Ox ay aw x and substitute into and ax 2