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← IIT-JEE 2008 · Paper 2
MathematicsAssertion and reason+3 / -1Question 11 of 66

IIT-JEE 2008 · Paper 2, Mathematics question 11

Let a,b,c,p,qa,b,c,p,q be real numbers. Suppose α,β\alpha,\beta are the roots of the equation x2+2px+q=0x^2+2px+q=0 and α,1β\alpha,\frac1\beta are the roots of the equation ax2+2bx+c=0ax^2+2bx+c=0, where β2∉{−1,0,1}\beta^2\notin\{-1,0,1\}.

STATEMENT-1: (p2−q)(b2−ac)≥0(p^2-q)(b^2-ac)\ge0

and

STATEMENT-2: b≠pab\ne pa or c≠qac\ne qa

Choose one option
Answer and worked solution

Official answer: B

Statement 2. If both b=pab=pa and c=qac=qa, the two equations would be the same, so {α,β}={α,1β}\{\alpha,\beta\}=\{\alpha,\frac1\beta\}, forcing β2=1\beta^2=1: excluded. So b≠pab\ne pa or c≠qac\ne qa. True.

Statement 1. If α were non-real, then β=αˉ\beta=\bar\alpha (real coefficients), and the second equation's roots α\alpha and 1αˉ\frac1{\bar\alpha} would also have to be conjugates, so 1αˉ=αˉ\frac1{\bar\alpha}=\bar\alpha, i.e. β2=1\beta^2=1: excluded. So all roots are real, both discriminants 4(p2−q)4(p^2-q) and 4(b2−ac)4(b^2-ac) are ≥0\ge0, and their product is ≥0\ge0. True.

Explanation? Statement 2 is not the reason for Statement 1.

(B)