Question

The equation of the plane containing the line $r=i+j+\lambda (2i+j+4k)$ is

• A. $r.(i+2j-k)=3$
• B. $r.(i+2j-k)=6$
• C. $r.(-i-2j+k)=3$
• D. None of the above

Answer 1

Answer: (A)

The position vector of any point on the given line is
$i+j+\lambda (2i+j+4k)$
or $(2\lambda +1)i+(\lambda +1)\hat{j}+4\lambda k$
which lies on $r.(i+2j+k)=3$
Hence, the plane
$r.(i+2j-k)=3$
contains the given line.