Find all real number x such that [2,-1,3] and [x,-2,1] are orthogonal.
I saw an example that just simply used dot product
$[2, -1, 3] \cdot [x, -2, 1]$ = $2x + 2 + 3 = 2x + 5$
The two vectors will be orthogonal when this dot product is zero. I'm not understanding the question all too well because apparently it is orthogonal
Best Answer
Yes, the two vectors are orthogonal if and only if the dot product is zero. From that you find that they are orthogonal if and only if $x = -\frac{5}{2}$. And that's it basically.