Question

If the vectors 2i + 3j+ k, 21 + pj + 3k and 2 + 17j – 3k are coplanar, then the value of p is​

Answer 1

Answer:

Three vectors, a, b, c are coplanar if [abc]=0

or

∣

∣

∣

∣

∣

∣

∣

∣

2

1

3

−1

2

λ

1

−3

5

∣

∣

∣

∣

∣

∣

∣

∣

=0

or 2(10+3λ)+1(5+9)+1(λ−6)=0 ( expanding along first row.)

or 7λ+28=0∴λ=−4