The vectors `a=hati+hatj+mhatk, b=hati+hatj+(m+1)hatk and c=hati-hatj+mhatk` are coplanar, it m is equal to

Options

A. 1
B. 4
C. 3
D. no value of m for which vectors are coplanar

Answer

D

Explanation

Given vectors are coplanar, if
`|(1,1,m),(1,1,m+1),(1,-1,m)|=0implies|(0,0,-1),(1,1,m+1),(1,-1,m)|=0
[R_(1)rarrR_(1)-R_(2)]`
`implies -1(-1-1)=0`
`implies 2 ne 0`
`therefore` No value of m for which vectors are coplanar.