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JEE MAIN 2019
09-01-19 S2
Question
The number of all possible positive integral values of $\alpha$ for which the roots of the quadratic equation, $6 x^2-11 x+ \alpha=0$ are rational numbers is
Select the correct option:
A
4
B
5
C
2
D
3
✓ Correct! Well done.
✗ Incorrect. Try again or view the solution.
Solution
The roots of $6 x^2-11 x+\alpha=0$ are rational numbers. ∴ Discriminant D must be perfect square number. $$ \begin{aligned} & D=(-11)^2-4 \cdot 6 \cdot \alpha \\ = & 121-24 \alpha \text { must be a perfect square } \\ \therefore & \alpha=3,4,5 \end{aligned} $$ $\therefore 3$ positive integral values are possible.
Question Tags
JEE Main
Mathematics
Easy
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