Question

Assertion (A): The joint equation of lines $y=x$ and $y=-x$ is $y^2=-x^2$ i.e. $x^2+y^2=0.$
Reason (R):The joint equation of lines $ax+by=0$ and $cx+dy=0.$ is $(ax+by)(cx+dy)=0$ where $a,b,c,d$ are constants.

• A. Both assertion and reason are true and reason is the correct explanation for assertion.
• B. Both assertion and reason are true but reason is not the correct explanation for assertion.
• C. Assertion is correct but reason is correct.
• D. Assertion is incorrect but reason is correct.

Answer 1

The correct option is D Assertion is incorrect but reason is correct.

Assertion: $y=x$ and $y=-x,$ then the pair of lines is $(y-x)(y+x)=0$
$y^2-x^2=0$. Hence, Assertion is false
Reason : Joint equations of lines $ax+by=0$ and $cx+dy=0$ is
$(ax+by)(cx+dy)=0$ where, $a,b,c$ and $d$ are constant. Hence, the Reason is true.