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JEE Main202125 Jul 2021Evening ShiftMathematicsStraight LinesActual

Let the equation of the pair of lines, y = p x and y = q x , can be written as y - p x y - q x = 0 . Then the equation of the pair of the angle bisectors of the lines x 2 - 4 x y - 5 y 2 = 0 is:

Options

  1. Ax 2 - 3 x y + y 2 = 0
  2. Bx 2 + 4 x y - y 2 = 0
  3. Cx 2 + 3 x y - y 2 = 0
  4. Dx 2 - 3 x y - y 2 = 0

Correct answer

C. x 2 + 3 x y - y 2 = 0

Step-by-step solution

We have, equation of a pair of lines x 2 - 4 x y - 5 y 2 = 0 Now, equation of bisector of a pair of lines x 2 - y 2 1 - - 5 = x y - 2 ⇒ x 2 - y 2 6 = x y - 2 ⇒ x 2 - y 2 = - 3 x y ⇒ x 2 + 3 x y - y 2 = 0 .

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