NTA Abhyas JEE Main2020MathematicsQuadratic EquationPractice
If both the roots of the equation 4 x 2 - 2 x + m = 0 lie in the interval - 1,1 , then
Options
- A- 3 < m < - 2
- B0 < m < 2
- C2 < m < 5 2
- D- 2 < m ≤ 1 4
Correct answer
D. - 2 < m ≤ 1 4
Step-by-step solution
Coefficient of x 2 is positive So, D ≥ 0 , f 1 > 0 , f - 1 > 0 D ≥ 0 ⇒ 4 - 4 × 4 × m ≥ 0 ⇒ m ≤ 1 4 f - 1 > 0 ⇒ 4 + 2 + m > 0 ⇒ m > - 6 f 1 > 0 ⇒ 4 - 2 + m > 0 ⇒ m > - 2 Taking intersection we get m ∈ - 2 , 1 4