Question

What is the value of $\lambda$ if the straight line $(2+4x+3y)+\lambda (6x-y+12)=0$ is parallel to y-axis.

• A. $3$
• B. $-6$
• C. $4$
• D. $-3$

Answer 1

Answer: (A)

$3$

$(2+4x+3y)+\lambda (6x-y+12)=0\Rightarrow (2+12\lambda )+(4+6\lambda )x+(3-\lambda )y=0$
For the line to be parallel to $y$-axis, co-efficient of $y$ should be $0$.
Then, $(3-\lambda )=0\Rightarrow \lambda =3$
Option A is true