MHT CET2019Morning ShiftMathematicsPair of LinesActual
The joint equation of lines passing through origin and having slopes 1 + 2 and - 1 1 + 2 is …
Options
- Ax 2 + 2 x y - y 2 = 0
- Bx 2 - 2 2 x y - y 2 = 0
- Cx 2 - 2 2 x y + y 2 = 0
- Dx 2 + 2 x y + y 2 = 0
Correct answer
A. x 2 + 2 x y - y 2 = 0
Step-by-step solution
It is given that slopes of the lines passing through origin are m 1 l e t = 1 + 2 a n d m 2 l e t = - 1 1 + 2 = - 2 - 1 ∴ Required joint equation of lines passing through origin is y - 1 + 2 x y + 2 - 1 x = 0 ⇒ y 2 + 2 - 1 x y - 1 + 2 x y - 2 - 1 x 2 = 0 ⇒ y 2 - 2 x y - x 2 = 0 ⇒ x 2 + 2 x y - y 2 = 0