Compute the line integral of F = <X^3, 4X> along the path from A to B. The path from A to B is not closed, it starts at A which has coordinates (-1,0) goes to (1,0) then goes up to (1,1) then left to (-2,1) then down to (-2,-1) and finally stops at B at (-1,-1).
Hint: To save work, use Green's Theorem to relate this time integral to the line integral along the vertical path from B to A.