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AP EAMCET · Maths · Parabola

If \(\left(x_1, y_1\right)\) and \(\left(x_2, y_2\right)\) are the end points of a focal chord of the parabola \(y^2=5 x\), then \(4 x_1 x_2+y_1 y_2\) is equal to

  1. A \(25\)
  2. B \(5\)
  3. C \(0\)
  4. D \(\frac {5}{4}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(0\)

Step-by-step Solution

Detailed explanation

Given parabola \(y^2=5 x\) Let \(\left(x_1, y_1\right)\) and \(\left(x_2, y_2\right)\) be the end points of a focal chord. So, \(x_1=\frac{5}{4} t_1^2\) and \(y_1=\frac{5}{4} t_1\) Since, \(t_1 t_2=-1\) as \(t_1\) and \(t_2\) are the end points of a focal chord…