QQuestion
The roots of the equation px² − qx + r = 0 are real and equal if:
(a) p² = 4qr
(b) q² = 4pr
(c) −q² = 4pr
(d) p² > 4qr
ICSEClass 10MathematicsQuadratic Equations01 Mark2024 Easy
✓Answer
(b) q² = 4pr
Explanation:
For a quadratic equation ax² + bx + c = 0, the roots are real and equal when the discriminant is zero.
D = b² − 4ac
Here, a = p, b = −q and c = r.
Therefore,
D = (−q)² − 4pr
⇒ D = q² − 4pr
For equal roots:
q² − 4pr = 0
⇒ q² = 4pr
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