Question

For which values of x are the given vectors u=xi−2j and v=xi+8j orthogonal?

Answer 1

+ - 4

Answer 2

The vectores are orthogonal if \[\langle u, v \rangle = x \cdot x + (-2) \cdot 8 = x^2 - 16 = 0\]so the solutions are\[x = \pm 4.\]

Answer 3

i guess those weird brackets denote dot productions?

Answer 4

Yes, those weird brackets denote dot product.