NTA Abhyas JEE Main2020MathematicsQuadratic EquationPractice
The least integral value of a for which the graphs y = 2 a x + 1 and y = a - 6 x 2 - 2 do not intersect is
Options
- A- 6
- B- 5
- C3
- D2
Correct answer
B. - 5
Step-by-step solution
a - 6 x 2 - 2 = 2 a x + 1 a - 6 x 2 - 2 a x - 3 = 0 Since the graphs do not intersect, ∴ D < 0 ⇒ 4 a 2 + 4 × 3 a - 6 < 0 ⇒ a 2 + 3 a - 18 < 0 ⇒ a + 6 a - 3 < 0 ⇒ a ∈ - 6 , 3 Hence, the least integer value of a is - 5