Find the equation of the tangent plane to the surface z=f(x,y)=x3−2xy+y2z = f(x, y) = x^3 - 2xy + y^2z=f(x,y)=x3−2xy+y2 at the point (1,2,1)(1, 2, 1)(1,2,1).
z−1=−(x−1)+2(y−2)z - 1 = -(x - 1) + 2(y - 2)z−1=−(x−1)+2(y−2)
z−1=−x+2y−2z - 1 = -x + 2y - 2z−1=−x+2y−2
z=−x+2y−2z = -x + 2y - 2z=−x+2y−2
z=−x+2y+1z = -x + 2y + 1z=−x+2y+1