Given the surfacez=f(x,y)=x^3+x^2+5xy+3y^2,
a) Enter the coordinates of the point on the surface where x=1and y=2?
b) Hence enter the equation of the plane that is tangent to z=f(x,y)at that point. For example, if your equation of the plane is 2x+y+z-5=0,enter 2*x+y+z-5?