1. The problem statement, all variables and given/known data Find the slope of tangent line to curve that is intersection to the surface z= (x^2) - (y^2) with plane x =2 , at point (2,1,3) The ans given by the author is only∂z /∂y = -2 2. Relevant equations 3. The attempt at a solution Is my diagram correct ? I'm wondering , why shouldnt we move the entire graph 'forward ' to x = 2 ?