NTA Abhyas JEE Main2020MathematicsParabolaPractice
The line y = 2 x + C is a tangent to the parabola y 2 − 4 y − 8 x = 4 at a point whose abscissa is α , then the ordered pair α , C is
Options
- A− 1 2 , 4
- B− 1 2 , 5
- C4 ,   5
- D− 1 2 , 1 2
Correct answer
B. − 1 2 , 5
Step-by-step solution
Equation of parabola is y − 2 2 = 8 x + 1 So, equation of tangent with slope 2 is y − 2 = 2 x + 1 + 2 2 ⇒ y = 2 x + 5 ⇒ C = 5 Point of contact is − 1 2 , 4 ⇒ α = − 1 2