WBJEE · Maths · Parabola
The maximum number of common normals of \(y^2=4 a x\) and \(x^2=4 b y\) is equal to
- A \(3\)
- B \(4\)
- C \(5\)
- D \(6\)
Answer & Solution
Correct Answer
(C) \(5\)
Step-by-step Solution
Detailed explanation
\(\mathrm{y}^2=4 \mathrm{ax} \text { and } \mathrm{x}^2=4 \mathrm{by}\) Eq. of normal to \(y^2=4 a x\) and \(x^2=4 b y\) are \(y=m x-2 a m-a m^3\) and \(y=m x+2 b+\frac{b}{m^2}\) For common normal; \(2 \mathrm{~b}+\frac{\mathrm{b}}{\mathrm{m}^2}+2 \mathrm{am}+\mathrm{am}^3=0\)…
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