1. Find an equation of the tangent plane to the surface a = a: mate: + ya} (JR. 2 =]n{13 33;} at the paint [ l _. 17 1]: (JR. {J51 LIHEEH where the equation at the tangent plane is. in general1 given by z - in = f1{3y}{m In} + fyiinytfniitr an}