Find a b, 4a 2b, | a |, and | a - b |. a = (- 3, 4), b = <9, - 1) a = 5i 3j, b = -i - 2j a = 4i - 3j 2k, b = 2i - 4k a = (8, 1, - 4), b = (5, - 2, 1)