The Discriminant - Worksheet 9 - 9th Grade

Hard

Use the discriminant to determine the nature of solutions (Hard)

23 problems · 15-20 minutes · Skills: quadratics, discriminant, algebra

About This Worksheet

This hard-level worksheet contains 23 problems designed for 9th Grade students practicing the discriminant. Hard worksheets feature challenging problems including multi-step questions, missing values, and real-world applications to push students further.

The discriminant provides instant insight into the nature of solutions without solving the entire equation. This efficiency is valuable in applied mathematics, and the concept of using a derived quantity to classify solutions generalizes throughout advanced mathematics.

  • Calculate the discriminant b² − 4ac from a quadratic in standard form
  • Determine whether a quadratic has two real, one real, or no real solutions
  • Connect the discriminant to the number of x-intercepts on a parabola's graph
  • Use the discriminant to decide which solving method to apply before attempting a solution
  • Identify the discriminant value that indicates a perfect square trinomial

How to Solve: Worked Example

Example Problem: Find the discriminant of 2x² + 20x + 50 = 0 and describe the roots.
Solution Steps:
  1. b² - 4ac = 400 - 4(2)(50) = 400 - 400 = 0.
  2. A zero discriminant means exactly one real solution.
  3. That root is repeated — the parabola touches the x-axis at a single point.
Answer: 0, one real solution
Tip: A discriminant of zero means the quadratic is a perfect square, and the vertex sits on the x-axis.
1
Find the discriminant and describe the roots: x² + 2x = 0
2
Find the discriminant and describe the roots: 2x² + 20x + 50 = 0
3
Find the discriminant and describe the roots: 2x² + 4x + 2 = 0
4
Find the discriminant and describe the roots: 3x² + 12x + 18 = 0
5
Find the discriminant and describe the roots: 3x² + 24x + 48 = 0
6
Find the discriminant and describe the roots: 2x² + 8x + 6 = 0
7
Find the discriminant and describe the roots: x² + 8x + 19 = 0
8
Find the discriminant and describe the roots: 3x² + 12x + 9 = 0
9
Find the discriminant and describe the roots: x² + 8x + 17 = 0
10
Find the discriminant and describe the roots: 3x² + 6x + 4 = 0
11
Find the discriminant and describe the roots: 3x² + 6x + 3 = 0
12
Find the discriminant and describe the roots: 3x² + 18x + 32 = 0
13
Find the discriminant and describe the roots: 3x² + 6x + 3 = 0
14
Find the discriminant and describe the roots: 3x² + 18x + 25 = 0
15
Find the discriminant and describe the roots: 2x² + 8x + 10 = 0
16
Find the discriminant and describe the roots: 2x² + 4x + 2 = 0
17
Find the discriminant and describe the roots: 3x² + 24x + 45 = 0
18
Find the discriminant and describe the roots: 2x² + 8x + 5 = 0
19
Find the discriminant and describe the roots: 3x² + 18x + 25 = 0
20
Find the discriminant and describe the roots: 3x² + 18x + 27 = 0
21
Find the discriminant and describe the roots: 2x² + 12x + 18 = 0
22
Find the discriminant and describe the roots: 3x² + 12x + 10 = 0
23
Find the discriminant and describe the roots: x² + 10x + 19 = 0

Answer Key

1. 4, two real solutions2. 0, one real solution3. 0, one real solution4. -72, no real solutions5. 0, one real solution6. 16, two real solutions7. -12, no real solutions8. 36, two real solutions9. -4, no real solutions10. -12, no real solutions11. 0, one real solution12. -60, no real solutions13. 0, one real solution14. 24, two real solutions15. -16, no real solutions16. 0, one real solution17. 36, two real solutions18. 24, two real solutions19. 24, two real solutions20. 0, one real solution21. 0, one real solution22. 24, two real solutions23. 24, two real solutions

Frequently Asked Questions

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What skills does this quadratic functions worksheet cover?

This worksheet focuses on quadratics, discriminant, algebra. It is designed for 9th Grade students and provides structured practice through varied problem types with a worked example to guide students before they begin.

Can I use this worksheet in my classroom?

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How many problems are on this worksheet?

This worksheet contains 23 problems. It typically takes 15-20 minutes to complete. An answer key with all solutions is included so parents and teachers can check work quickly.