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AP EAMCET · Maths · Parabola

If the line \(y=2 x+k\) is normal to the parabola \(y^2=4 x\), then \(k=\)

  1. A -10
  2. B 10
  3. C 12
  4. D –12
Verified Solution

Answer & Solution

Correct Answer

(D) –12

Step-by-step Solution

Detailed explanation

Since, equation of normal to the parabola \(y^2=4 a x\) having slope \(m\) is \(y=m x-2 a m-a m^3\). So, equation of normal to the parabola \(y^2=4 x\) is \[ y=2 x+k \] Therefore, \[ \begin{aligned} k & =-2(1)(2)-(1)(2)^3 \\ & =-4-8=-12 \end{aligned} \] Hence, option (4) is…