Given the two displacements D = (6i^ + 3j^ - K^)m and E = (4i^ - 5j^ + 8k)m

Find magnitude of displacement 2D - E

F = 2(6i^ + 3j^ - K^)m - (4i^ - 5j^ + 8k)m =

[(12 - 4)i^ + (6 + 5)j^ + (-2 - 8)k^]m

= (8i^ + 11j^ - 10k^)m

F = sqrt{Fx^2 + Fy^2 + Fz^2} =

sqrt{(8m)^2 + (11m)^2 + (-10m)^2 = 17m}

Nevermind. I understand now.