The correct option is B 3x+4y=35
We have, 6x2−xy−12y2=0
⇒(2x−3y)(3x+4y)=0 ...... (i) and
15x2+14xy−8y2=0
⇒(5x−2y)(3x+4y)=0 ...... (ii)
Equation of the line common to (i) and (ii) is
3x+4y=0 ....... (iii)
Equation of any line parallel to (iii) is
3x+4y=k
Since its distance from (iii) is 7, so
∣∣
∣∣k√32+42∣∣
∣∣=7⇒k=±35
Therefore, the equation of required line is 3x+4y=35.