8) Find the directional derivative of f (x, y, z) : 34322 + way6 in the direction of v: 6i3j+2k. (8 pts) 9) Find the equation of the plane tangent to and the line (in symmetric form) normal to the ellipsoid Jr:2 +4322 +8.-2 : 48 at the point (2,3,1] . (10 pts) 10) Find a unit vector in the direction that f (x, y, z) : 2x2 + 6x322 x23 increases most rapidly at the point [3,4,4) and nd the rate of increase in that direction. (8 pts)