Question

If the pair of straight lines 6x2 +14xy+ky2 =0 are at right angles, find k.​

Answer 1

Answer:

The answer is $-6$

Step-by-step explanation:

    Concept : If the angle between the pair of line represented by                                  

                $ax^2+by^2+2hxy+2gx+2fy+c=0$ is $90^\circ$, then $a+b=0$

    Here given angle between the lines represented by

        $6x^2+14xy+ky^2=0$ is $90^\circ$ (right angle)

                   $\Rightarrow 6+k=0\Rightarrow k=-6$