In Problems 1-3 we will be finding the tangent plane to a surface given by the equation f(x,y) xy x+y at the point (1,2,3) without using the formula given in class. 1. (2 points) Find fx(1,2) and fy(1,2). 2. (1 point) The x-direction tangent line vector is given by (1,0, f,(1,2)), and the y-direction tangent line vector is given by (0,1,f,(1,2)). After plugging in your answers from Question 1, find the cross product of these two vectors. 3. (1 point) Find the equation of the plane at the point (1,2,3) with normal vector given by the vector you got in Question 2. Write your answer in the form z = ax+by+c for some constants a, b, and c. (This is the tangent plane to the function at this point, so you can check your work using a formula we have learned in class.)