Question

If in general quadratic equation $f\left(x,y\right)=0,∆=0,$ and $a+b=0$, then the equation represents

• A. Two parallel straight lines
• B. Two perpendicular straight lines
• C. Two lines passing through the origin
• D. None of these

Answer 1

The correct option is B

Two perpendicular straight lines

Explanation for the correct option.

Find the type of conic the equation represents.

For the given general quadratic equation $f\left(x,y\right)=0$, it is given that $∆=0$ and so the equation represents a pair of straight lines.

It is also given that $a+b=0$, so the pair of straight lines are also perpendicular to each other.

Thus the equation represents two perpendicular straight lines.

Hence, the correct option is B.