a) Find the directional derivative of the function at the given points in the direction of vector v. h(x, y, z) = cos(xy) + ey² + Inyz, Po(1,0, ¹/2), v = i + 2j+2k. b) Find the local extreme values of f(x,y) = x² + 3xy + 3y² - 6x + 3y - 6. Solution # 5 (to be typed here by the student)

Use the definition of directional derivative to solve Duf(xo, Yo, zo) at point P(xo, Yozo) where f(x, y, z) = x² + y² + z² + 2xz and u = = (1,0, 1) at P(1, 1, 1).