\fwhich of the following is equivalent to u - v? 6. 1. 106 10.0 points Determine the length of the vector a - 2b when 2. a = (3,2, -1), b = (-1,3, -1). 1. length = v38 2. length = 2VII 3. length = 6 4. length = 2v 10 5. length = v42 007 10.0 points 3. Find all scalars Aso that A(2a + b) is a unit vector when a = (1,3), b = (-1, -3). 1. A = 1 2. A = 1- 4. 3. A -+- 1 4. A - 5. A= 6. A =