Two vectors in R3\mathbb{R}^3R3 are given, one of them depending on an unknown scalar kkk:
u=(2, −3, 1),v=(k, 4, 2k)\mathbf{u} = (2,\ -3,\ 1), \qquad \mathbf{v} = (k,\ 4,\ 2k)u=(2, −3, 1),v=(k, 4, 2k)
For which value of kkk are u\mathbf{u}u and v\mathbf{v}v orthogonal?
Select all that apply.
k=4k = 4k=4
k=8k = 8k=8
k=−3k = -3k=−3
k=3k = 3k=3