DepEd MELC reviewer for Grade 9 Mathematics, Quarter 1. Study the rules, worked formulas, and exam hacks below.
1
Forms and Methods of Solving
Standard form: ax² + bx + c = 0. Solve by extracting roots, factoring, completing the square, or the quadratic formula.
x = [ −b ± √(b² − 4ac) ] ÷ 2a
2
Nature of the Roots (Discriminant)
| Discriminant b²−4ac | Roots |
|---|---|
| > 0 (perfect square) | 2 real, rational |
| > 0 (not perfect square) | 2 real, irrational |
| = 0 | 1 real (double) root |
| < 0 | No real roots |
💡 Exam Hack
Check the discriminant FIRST to know how many roots to expect before solving.
3
Sum and Product of Roots
Sum of roots = −b/a | Product of roots = c/a
4
Worked Example
Solve x² − 5x + 6 = 0 by factoring.
(x − 2)(x − 3) = 0 → x = 2 or x = 3
Set each factor to zero. Check the discriminant: 25 − 24 = 1 > 0 → two real roots.
📌 Quick Recap — Master These
Before your test, make sure you can confidently do each of the following:
- Explain and apply Forms and Methods of Solving.
- Explain and apply Nature of the Roots (Discriminant).
- Explain and apply Sum and Product of Roots.
- Explain and apply Worked Example.
Re-read any section above where you hesitate, then try the worked example again without looking.