JEE MainMathematicsQuadratic Equation and InequalitiesNumerical+4 / −1
The least positive value of 'a' for which the equation 2x2 + (a – 10)x + = 2a has real roots is
Numerical answer
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Correct answer: 8
We need the least positive value of such that the quadratic equation has real roots.
1. Rewrite the equation in standard quadratic form
Given:
Bring all terms to one side:
So the quadratic is:
Here,
2. Condition for real roots
For a quadratic equation to have real roots, its discriminant must satisfy:
So,
Substitute the values:
3. Simplify the discriminant
First compute:
Thus,
Expand:
Factorize:
Hence,
4. Solve the inequality
Critical points are and .
So,
We need the least positive value of .
Therefore,
5. Compare with stored answer
Stored correct answer:
Our derived answer is also , so they agree.
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