Question

If $2i+j-k$ and $i-4j+\lambda k$ are perpendicular to each other, then $\lambda$ is equal to:

• A. $-3$
• B. $-2$
• C. $-1$
• D. $0$

Answer 1

The correct option is B $-2$

Since, given vectors are perpendicular.
$\therefore (2i+j-k).(i-4j+\lambda k)=0$
$\Rightarrow 2-4-\lambda =0$
$\Rightarrow \lambda =-2$