9. Consider the curve, C. which is part of the parabola with equation y = z as shown below (note that the curve begins at the point with co-ordinates (2. 4) and ends at the point with co-ordinates (0. 0)): (2. 4) (0.0) Let F(r. y) - -( + y) i + Arj be a vector field in R- (a) Explain why r(t) = (x(1), y(0)) - (2-1. (2-0)3) -(2-12-(2-1)-j. for 0