Question

The image of the pair of lines represented by$a{x}^2+2hxy+b{y}^2=0$ by the line $y=0$ mirror is:

• A. $a{x}^2-2hxy-b{y}^2=0$
• B. $b{x}^2-2hxy+a{y}^2=0$
• C. $b{x}^2+2hxy+a{y}^2=0$
• D. $a{x}^2-2hxy+b{y}^2=0$

Answer 1

The correct option is D $a{x}^2-2hxy+b{y}^2=0$

In ${ax}^2+2hxy+{by}^2=0$ replacing $y$ by $-y$
we get, ${ax}^2+2hx(-y)+{by}^2=0$
$\Rightarrow {ax}^2-2hxy+{by}^2=0$