Question

If the two vectors ¯a=2^i+3^j+4^ and ¯b=^i+2^j−n^k are perpendicular, then the value of n is:

Answer 1

$a.b = 0 \\ (2i + 3j + 4k).(i + 2j - nk) = 0 \\ 2 + 6 - 4n = 0 \\ n = \frac{8}{4} = 2$