Question

Point T is the midpoint of a straight line AB. Given the position vectors of A and T are i - j + k and 2i + 1 ½ k respectively, find the position vector of B in terms of i, and k

Answer 1

T = A+(B-A)/2 = (A+B)/2
B = 2T-A

Answer 2

so B = (3, 1, 2)