MHT CET202124 Sep 2021Morning ShiftMathematicsPair of LinesActual
The joint equation of pair of lines through the 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
C. x^2-2 2 x y+y^2=0
Step-by-step solution
1 1+ 2 = ( 2 -1) ( 2 +1)( 2 -1) = 2 -1 2-1 = 2 -1 Hence equations of lines passing through origin and having slopes ( 2 +1) and ( 2 -1) are y =( 2 +1) x and y =( 2 -1) x Their joint equation is [( 2 +1) x - y ][( 2 -1) x - y ]=0x^2-2 2 x y+y^2=0