Question

Find $k$ if magnitude of vectors joining $(0,k,0)$ and $(1,1,1)$ is $\sqrt{11}$

• A. $-3$
• B. $2$
• C. $-2$
• D. $0$

Answer 1

The correct option is C $-2$

Using definition of magnitude, we have

$11=1+$ $(k-1{)}^2$ $+1$

So $(k-1{)}^2$ $=9$

$\Rightarrow k^2-2k+1-9=0$

$\Rightarrow k=+4$ or $-2$

So, the answer is $-2$.