1. approximate ( sin 1) e by using the differential of the function f(x,y ) = (sinx.) ey at (3TT, 0) (8 points) 2 . For the function f(x, y ) = x3 - 2 xy + 3y? find the direction and magnitude of the maximum rate of increase at (2, 1). (5 points) 3. Calculate the u- directional derivative at (0, 0) in each case. ( 6 pets. each) , ( x,y ) * (0,0), (a) f(x, y )= X (x ,y ) = (0,0), (b ) f (x,y ) = 5x+ 7 x M = ( x - 1 ) 2 - y