3. Given is the function f : Df → R with F(x1, x2, x3) = x 2 1 +
2x 2 2 + x 3 3 + x1 x3 − x2 + x2 √ x3 . (a) Determine the gradient
of function F at the point x 0 = (x 0 1 , x0 2 , x0 3 ) = (8, 2,
4). (b) Determine the directional derivative of function F at the
point x 0 in the direction given...