JEE Main 2013MathematicsCircleHardMCQ

JEE Main 2013Circle Question with Solution

JEE Main 2013 (07 Apr)

Question

Given : A circle, 2x2+2y2=5 and a parabola, y2=45x.

Statement - I : An equation of a common tangent to these curves is y=x+5.

Statement - II : If the line, y=mx+5m m0  is their common tangent, then m satisfies m4-3m2+2=0.

Choose an option

Show full solutionCorrect option: D
Correct answer
DStatement - I is true; Statement - II is true; Statement - II is not a correct explanation for statement - I.

Step-by-step explanation

Tangent to y2=45x will be y=mx+5m 
As tangent to x2+y2=52 will be y=mx±521+m2
Hence for common tangent

5m=521+m2
m4+m2-2=0

m2=1 , m2=2 (Not Possible)

m=±1
Hence common tangent is y=x+5

Both the statements are correct

The values of m also satisfy the equation in statement - II but it is not a correct explanation for statement - I

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About this question

This is a previous-year question from JEE Main 2013, covering the Circle chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.