Question

find m,p=i-j+2k and Q=3i+mj-k are perpendicular to one another ​

Answer 1

P = i-j+2k

Q = 3i+mj-k

P•Q = 0

(because when 2 vector are perpendicular the they are equal to Cos 90° that is 0)

1×3-1×m-1×2 = 0

3-m-2 = 0

1-m = 0

-m = -1

m = 1

Therefore, value of m = 1