Mathematics · Quadratic Equations

JEE Main 2026 — 28 January, Morning Shift — Question 10

If α,β\alpha, \beta ,where α<β\alpha<\beta ,are the roots of the equation λx2−(λ+3)x+3=0\lambda \mathrm{x}^{2}-(\lambda+3) \mathrm{x}+3=0 such that 1α−1β=13\frac{1}{\alpha}-\frac{1}{\beta}=\frac{1}{3}, then the sum of all possible values of λ\lambda is :

  1. Option A:

    6

    Correct
  2. Option B:

    2

  3. Option C:

    4

  4. Option D:

    8

Answer: A

Step-by-step solution

β−ααβ=13,α+β=λ+3λ,αβ=3λ\frac{\beta-\alpha}{\alpha \beta}=\frac{1}{3}, \quad \alpha+\beta=\frac{\lambda+3}{\lambda}, \alpha \beta=\frac{3}{\lambda}

β−α=αβ3=1λ\beta-\alpha=\frac{\alpha \beta}{3}=\frac{1}{\lambda}

on squaring

α2+β2−2αβ=1λ2\alpha^{2}+\beta^{2}-2 \alpha \beta=\frac{1}{\lambda^{2}}

α2+β2+2αβ=(λ+3)2λ2….(2) \alpha^{2}+\beta^{2}+2 \alpha \beta=\frac{(\lambda+3)^{2}}{\lambda^{2}} \ldots . (2)

4αβ=(λ+3)2−1λ24 \alpha \beta=\frac{(\lambda+3)^{2}-1}{\lambda^{2}}

12λ=λ2+6λ+8λ2\frac{12}{\lambda}=\frac{\lambda^{2}+6 \lambda+8}{\lambda^{2}}

⇒λ3−6λ2+8λ=0\Rightarrow \lambda^{3}-6 \lambda^{2}+8 \lambda=0

\tag\ldots \Rightarrow \lambda=0,2,4

Sum of possible values of λ\lambda is =6=6

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Subject
Mathematics
Chapter
Quadratic Equations
Topic
Nature of Roots of Quadratic Equation
If α, β ,where α<β ,are the roots of the equation λ x 2 -(λ+3) x +3=0… | JEE Main 2026 PYQ with Solution · DhiX AI