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Assertion (A): The roots of the quadratic equation $$3x^{2} + 7x + 8 = 0$$ are imaginary. Reason (R): The discriminant of a quadratic equation is always positive.

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Question

Assertion (A): The roots of the quadratic equation $$3x^{2} + 7x + 8 = 0$$ are imaginary.

Reason (R): The discriminant of a quadratic equation is always positive.

Options

  • Both A and R are true, and R is the correct explanation of A.

  • Both A and R are true, but R is not the correct explanation of A.

  • A is true, but R is false.

  • A is false, but R is true.

MCQ
Assertion and Reasoning
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Solution

A is true, but R is false.

Explanation:

Step 1 – Assertion: A is true. For the given equation, $$a = 3$$, $$b = 7$$ and $$c = 8$$. $$D = b^{2} - 4ac = 7^{2} - 4 \times 3 \times 8 = 49 - 96 = -47 < 0$$. A negative discriminant means the roots are unequal and imaginary.

Step 2 – Reason: R is false. The discriminant is not always positive; it can be positive, zero or negative. Here, it is $$-47$$.

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Chapter 5: Quadratic Equation - COMPETENCY-FOCUSED QUESTIONS [Page 69]

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R.S. Aggarwal Mathematics [English] Class 10 ICSE
Chapter 5 Quadratic Equation
COMPETENCY-FOCUSED QUESTIONS | Q 3. | Page 69
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