JEE Advanced 2015Paper 2
- Exam
- JEE Advanced
- Year
- 2015
- Paper
- Paper 2
- Subject
- Mathematics
- Chapter
- Quadratic Equation
JEE Advanced 2015 · Paper 2 · Mathematics · Quadratic Equation
Let S be the set of all non - zero real numbers α such that the...
Let S be the set of all non - zero real numbers such that the quadratic equation has two distinct real roots satisfying the inequality \left|{x}_{1} - {x}_{2}\right| < 1 .$ Which of the following intervals is(are) a subset(s) of S?
Options
- A
- B
- C
- D
Correct answer
A.
Step-by-step solution
\alpha{x}^{2} - x + \alpha = 0
\left|\dfrac{\sqrt{1 - 4{\alpha}^{2}}}{\alpha}\right| < 1\sqrt{1 - 4{\alpha}^{2}} < | \alpha |1 - 4{\alpha}^{2} < {\alpha}^{2}{\alpha}^{2} - \dfrac{1}{5} > 0\alpha \in \left(- \infty, - \dfrac{1}{\sqrt{5}}\right) \cup \left(\dfrac{1}{\sqrt{5}}, \infty\right)1 - 4{\alpha}^{2} > 0{\alpha}^{2} - \dfrac{1}{4} < 0
Taking intersection
\left|\dfrac{\sqrt{1 - 4{\alpha}^{2}}}{\alpha}\right| < 1\sqrt{1 - 4{\alpha}^{2}} < | \alpha |1 - 4{\alpha}^{2} < {\alpha}^{2}{\alpha}^{2} - \dfrac{1}{5} > 0\alpha \in \left(- \infty, - \dfrac{1}{\sqrt{5}}\right) \cup \left(\dfrac{1}{\sqrt{5}}, \infty\right)1 - 4{\alpha}^{2} > 0{\alpha}^{2} - \dfrac{1}{4} < 0
Taking intersection