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JEE Mains · Maths · STD 11 - 10.2 parabola,ellipse,hyperbola

यदि दीर्घवृत्त \(x ^2+4 y ^2+2 x +8 y -\lambda=0\) की नाभिलंब जीवा की लंबाई \(4\) है तथा इसके दीर्घअक्ष की लंबाई \(l\) है, तो \(\lambda+l\) बराबर है \(...........\)

  1. A \(72\)
  2. B \(73\)
  3. C \(74\)
  4. D \(75\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(75\)

Step-by-step Solution

Detailed explanation

\(\lambda+\ell=75\) \(x^{2}+4 y^{2}+2 x+8 y-\lambda=0\) \(\frac{(x+1)^{2}}{\lambda+5}+\frac{(y+1)^{2}}{\lambda+5}=1\) \(\because \frac{2 b^{2}}{a}=4\) \(\frac{2(\lambda+5)}{4}=4(\sqrt{\lambda+5})\) \(\lambda=59\) \(\lambda \neq-5\) \(l=2 a=2 \sqrt{\lambda+5}=2 \sqrt{65}=16\)…
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