JEE Main 201912 JanuaryMorning Shift
- Exam
- JEE Main
- Year
- 2019
- Date
- 12 January
- Shift
- Morning Shift
- Subject
- Mathematics
- Chapter
- Quadratic Equation
JEE Main 2019 · 12 January · Morning Shift · Mathematics · Quadratic Equation
If λ be the ratio of the roots of the quadratic equation in x, 3 m...
If be the ratio of the roots of the quadratic equation in , then the least value of for which , is :
Options
- A
- B
- C
- D
Correct answer
D.
Step-by-step solution
Let \beta3{m}^{2}{x}^{2} + m\left(m - 4\right)x + 2 = 0∴ \alpha + \beta = - \dfrac{m\left(m - 4\right)}{3{m}^{2}} \text{} \alpha\beta = \dfrac{2}{3{m}^{2}} . . . . . . . . . \left(i\right)\dfrac{\alpha}{\beta} = \lambda \text{} \lambda + \dfrac{1}{\lambda} = 1⇒ \dfrac{\alpha}{\beta} + \dfrac{\beta}{\alpha} = 1⇒ {\left(\alpha + \beta\right)}^{2} = 3\alpha\beta, we get
Hence, the least value of is .