EGR 511

7. Find the directional derivative of f(x, y) = 2x2 + y2 at x = 2 and y = 2 in the direction of h = 3i + 2j. Ans: 8.875. Solution. f(x, y) = 2x2 + y2 = 4x = 8 at x = 2 and y = 2 = 4y = 4 at x = 2 and y = 2 ( = tan-1 = 0.588. g’ = directional derivative. g’ = cos( + sin( = 8cos(0.588) + 4sin(0.588) = 8.875 8. ................
................