3. Consider the vector field F(x, y, z) = <2xy^3 + z^2, 3x^2y^2 + 2yz, y^2 + 2xz>
(a) Show that F is a conservative vector field and find a potential function f.
(b) Evaluate the line integral
∫_C F · dr,
where C is any path from (0, 1, -1) to (1, 2, 1).