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

Year 2026 2025 2024 Total
Questions 11 10 5 26

Let α and β be the roots of equation x² + 2ax + (3a + 10) = 0 such that α < 1 < β. Then the set of all possible values of a is:

Solution & Explanation

Related Formula
For ax²+bx+c=0 with a > 0 , if a point k lies strictly between the roots, f(k) < 0.
Core Logic

Given f(x) = x² + 2ax + (3a + 10). Since the coefficient of x² is 1 > 0, the parabola opens upward. For 1 to lie between the roots α and β, the value of the function at x = 1 must be strictly less than 0. f(1) < 0

Step 1: Evaluate Inequality
f(1) = 1² + 2a(1) + 3a + 10 < 0 1 + 2a + 3a + 10 < 0

5a + 11 < 0

a < -(11)/(5)

So, a in (-∞, -(11)/(5)).

Pattern Recognition

When a specified value k lies between roots, a · f(k) < 0. If a>0, this simplifies to f(k) < 0. No need to check discriminant Δ > 0 manually because a f(k) < 0 guarantees real distinct roots.

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_21_jan_evening

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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%)