Find the flux of the vector field F < y, z, x > across the part of the plane z = 1+2x+3y above the rectangle [0, 5] x [0, 4] with upwards orientation.

Consider the vector v=(1,3,0,4). Find u such that a u has the same direction as v and one-half of its length. b u has the direction opposite that of v and twice its length.