consider the curve given by the equation 3 y xy 2. it can be shown that 2 3 dy y dx y x . (a) write an equation for the line tangent to the curve at the point 1, 1 . (b) find the coordinates of all points on the curve at which the line tangent to the curve at that point is vertical. (c) evaluate 2 2 d y dx at the point on the curve where x 1 and y 1.