Class 10 Maths MCQs on Quadratic Formula and Nature of Roots
CBSE Class 10 Mathematics – Quadratic Formula & Nature of Roots MCQs
Chapter 4: Quadratic Equations
Topic: Quadratic Formula and Nature of Roots
Based on NCERT | As per Latest CBSE Board Examination Pattern
1. The quadratic formula for ax² + bx + c = 0 is:
Correct Answer: A
Explanation: The quadratic formula is x = (-b ± √(b² - 4ac)) / 2a.
Explanation: The quadratic formula is x = (-b ± √(b² - 4ac)) / 2a.
2. The expression b² − 4ac is called:
Correct Answer: C
Explanation: D = b² − 4ac is called the discriminant.
Explanation: D = b² − 4ac is called the discriminant.
3. If discriminant D > 0, roots are:
Correct Answer: B
Explanation: When D > 0, the equation has two distinct real roots.
Explanation: When D > 0, the equation has two distinct real roots.
4. If D = 0, roots are:
Correct Answer: B
Explanation: When D = 0, roots are real and equal.
Explanation: When D = 0, roots are real and equal.
5. If D < 0, roots are:
Correct Answer: C
Explanation: Negative discriminant means roots are not real.
Explanation: Negative discriminant means roots are not real.
6. Find discriminant of x² − 4x + 3 = 0.
Correct Answer: D
Explanation: D = (-4)² − 4(1)(3) = 16 − 12 = 4.
Explanation: D = (-4)² − 4(1)(3) = 16 − 12 = 4.
7. Nature of roots of x² − 4x + 3 = 0 is:
Correct Answer: B
Explanation: D = 4 > 0 ⇒ real and distinct roots.
Explanation: D = 4 > 0 ⇒ real and distinct roots.
8. Find discriminant of x² + 2x + 1 = 0.
Correct Answer: B
Explanation: D = 2² − 4(1)(1) = 4 − 4 = 0.
Explanation: D = 2² − 4(1)(1) = 4 − 4 = 0.
9. Nature of roots of x² + 2x + 1 = 0:
Correct Answer: A
Explanation: D = 0 ⇒ roots are real and equal.
Explanation: D = 0 ⇒ roots are real and equal.
10. Find discriminant of x² + x + 1 = 0.
Correct Answer: C
Explanation: D = 1² − 4(1)(1) = 1 − 4 = −3.
Explanation: D = 1² − 4(1)(1) = 1 − 4 = −3.
11. Nature of roots of x² + x + 1 = 0:
Correct Answer: C
Explanation: D < 0 ⇒ roots are not real.
Explanation: D < 0 ⇒ roots are not real.
12. Roots of 2x² − 3x − 2 = 0 are:
Correct Answer: A
Explanation: Using formula:
x = [3 ± √(9 + 16)]/4 = [3 ± 5]/4 ⇒ x = 2, −1/2.
Explanation: Using formula:
x = [3 ± √(9 + 16)]/4 = [3 ± 5]/4 ⇒ x = 2, −1/2.
13. If discriminant is perfect square and positive, roots are:
Correct Answer: B
Explanation: Perfect square D > 0 gives rational distinct roots.
Explanation: Perfect square D > 0 gives rational distinct roots.
14. If discriminant is positive but not perfect square, roots are:
Correct Answer: B
Explanation: √D will be irrational, so roots are irrational and distinct.
Explanation: √D will be irrational, so roots are irrational and distinct.
15. Find discriminant of 4x² − 4x + 1 = 0.
Correct Answer: A
Explanation: D = (−4)² − 4(4)(1) = 16 − 16 = 0.
Explanation: D = (−4)² − 4(4)(1) = 16 − 16 = 0.
16. Nature of roots of 4x² − 4x + 1 = 0:
Correct Answer: A
Explanation: D = 0 ⇒ roots equal.
Explanation: D = 0 ⇒ roots equal.
17. If a quadratic equation has no real roots, D is:
Correct Answer: C
Explanation: D < 0 ⇒ no real roots.
Explanation: D < 0 ⇒ no real roots.
18. Sum of roots using quadratic formula equals:
Correct Answer: B
Explanation: Sum of roots = −b/a.
Explanation: Sum of roots = −b/a.
19. Product of roots equals:
Correct Answer: C
Explanation: Product of roots = c/a.
Explanation: Product of roots = c/a.
20. Quadratic formula works for:
Correct Answer: C
Explanation: Quadratic formula can solve every quadratic equation.
Explanation: Quadratic formula can solve every quadratic equation.
