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Quadratic Equations appeared 26 times across 3 years — 3% of Mathematics. This question is from Difference of Roots Inequality.

Year 2026 2025 2024 Total
Questions 11 10 5 26

Let α, β be the roots of the quadratic equation 12x² - 20x + 3λ = 0, λ in Z. If (1)/(2) ≤ |β - α| ≤ (3)/(2), then the sum of all possible values of λ is:

Solution & Explanation

Related Formula

Difference of roots formula:

(α - β)² = (α + β)² - 4αβ

For 12x² - 20x + 3λ = 0: α + β = (20)/(12) = (5)/(3), αβ = (3λ)/(12) = (λ)/(4).

Core Logic

Square the inequality (1)/(2) ≤ |α - β| ≤ (3)/(2):

(1)/(4) ≤ (α - β)² ≤ (9)/(4) (1)/(4) ≤ (25)/(9) - λ ≤ (9)/(4) -(91)/(36) ≤ -λ ≤ -(19)/(36) (19)/(36) ≤ λ ≤ (91)/(36)
Step 1: Integer Values of Lambda

Since λ in Z, the valid integer values are λ = 1, 2.

Sum = 1 + 2 = 3
Pattern Recognition

Convert root difference inequality into quadratic discriminant bounds for quick integer extraction.

Chapter Mix

Class 11 Maths: Quadratic Equations

Reference Study Guides

More Quadratic Equations Previous-Year Questions — Page 6

Q20 jee_main_2024_31_jan_morning Sign of Quadratic Expressions
Let S be the set of positive integral values of a for which (ax² + 2(a + 1)x + 9a + 4)/(x² - 8x + 32) < 0, x in R. Then, the number of elements in S is:
  • A. 1
  • B. 0
  • C. ∞
  • D. 3

Solution

Core Logic

For the denominator x² - 8x + 32, D = 64 - 128 < 0 and a = 1 > 0. Thus, x² - 8x + 32 > 0 x in R.

Step 1: Constraint on Numerator

Since the denominator is always positive, the numerator must be strictly negative for all x in R.

ax² + 2(a + 1)x + 9a + 4 < 0 x in R

This requires a < 0 and D < 0.

Step 2: Conclusion

Since a must be strictly less than 0, there are no positive integral values of a that satisfy the condition. Hence, S is an empty set. Number of elements is 0.

Chapter Mix

Class 11 Maths: Quadratic Equations

More Quadratic Equations Questions — jee_main_2026_22_january_evening

Practice all Quadratic Equations previous-year questions →

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JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)