MHT CET2007MathematicsParabola
The equation to the line touching both the parabolas y²=4 x and x²=-32 y , is
Options
- Ax+2 y+4=0
- B2 x+y-4=0
- Cx-2 y-4=0
- Dx-2 y+4=0
Correct answer
D. x-2 y+4=0
Step-by-step solution
The equation of any tangent to the parabola y²=4 x is y=m x+ 1 m This touches the parabola x²=-32 y , therefore the equation x²=-32 (m x+ 1 m ) has equal roots (32 ~m )²=4 ( 32 ~m ) 8 m³=1 m= 1 2 On putting the value of m in Eq. (i), we get x-2 y+4=0