In Problems 1-3, find the tangent plane to the surface at point P 0

. 1. z=x 2
+xy+y 2
,P 0

(−1,1,1) 2. z=x 2
y+e xy
siny,P 0

(1,0,0) 3. z= y
x

+xy,P 0

(4,1,8)