Q.

If two vectors P=i^+2mj^+mk^ and Q=4i^2j^+mk^ are perpendicular to each other. Then, the value of m will be          [2023]

1 –1  
2 2  
3 3  
4 1  

Ans.

(2)

P·Q=0

(i^+2mj^+mk^)·(4i^2j^+mk^)=0  44m+m2=0

 (m2)2=0  m=2