Engineering
Mathematics
Inequalities
Question

If α, β are the roots of 3x2 – 5x + a = 0 and αβ+βα > 2, then

a < 0

0<a<754

a>754

0<a<2512

JEE Advance
College PredictorLive

Know your College Admission Chances Based on your Rank/Percentile, Category and Home State.

Get your JEE Main Personalised Report with Top Predicted Colleges in JoSA

Solution

Given quadratic: 3x² - 5x + a = 0 with roots α, β. Using sum and product formulas: α + β = 5/3, αβ = a/3.

The inequality simplifies to (α² + β²)/(αβ) > 2. Since α² + β² = (α+β)² - 2αβ, we get:

(α+β)2-2αβαβ>2

Substitute values: (53)2-2·a3a3>2

Solving gives: (25/9 - 2a/3)/(a/3) > 2 → (25 - 6a)/3a > 2 → 25 - 6a > 6a → 25 > 12a → a < 25/12

Since roots are real, discriminant ≥ 0: 25 - 12a ≥ 0 → a ≤ 25/12. Combining with a < 25/12 gives 0 < a < 25/12.

Final answer: 0<a<2512