Please help, thank you!

Question 12 (1 point) The length/magnitude of the vector C = (2, -3, 1) is Question 13 (1 point) If m72 = (2, 1, 5) and 12 = (3, 0, x) are perpendicular, then the value of x is Question 14 (1 point) To the nearest tenth, the angle between p = (1, -5) and V = (4, 6) is Question 15 (1 point) The cross product of vectors a= (-1, 4, 6) and b = (3, 0, -2) is