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Question: Answered & Verified by Expert
If $(3, \lambda \lambda \lambda \lambda)$ and $(5,6)$ are the conjugate points to the curve $x^{2}+y^{2}=3$, then $\lambda \lambda \lambda \lambda$ is
MathematicsCircleJEE Main
Options:
  • A $-1$
  • B 1
  • C $-2$
  • D 2
Solution:
2652 Upvotes Verified Answer
The correct answer is: $-2$
If the $(3, \lambda \lambda \lambda \lambda)$ and $(5,6)$ are the conjugate points to the curve $x^{2}+y^{2}=3$, then
$\begin{aligned} x_{1} x_{2}+y_{1} y_{2} &=3 \\ \Rightarrow \quad(3)(5)+(\lambda \lambda \lambda \lambda) \cdot(6) &=3 \end{aligned}$
$\Rightarrow \quad 15+6(\lambda \lambda \lambda \lambda)=3$
$\Rightarrow 6(\lambda \lambda \lambda \lambda)=-12$
$\Rightarrow \lambda \lambda \lambda \lambda=-2$

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