Use the fact that if AB = 0, then A = 0 or B = 0. Factor the left side to solve the equation.
📘 Example ①
Solve x² − 5x + 6 = 0.
Answer:(x − 2)(x − 3) = 0 → x = 2 or 3
Solve x² − 5x + 6 = 0.
Answer:(x − 2)(x − 3) = 0 → x = 2 or 3
📘 Example ②
Solve x² − 9 = 0.
Answer:(x + 3)(x − 3) = 0 → x = ±3
Solve x² − 9 = 0.
Answer:(x + 3)(x − 3) = 0 → x = ±3
💡 Key Points
- Make the right side 0 before factoring
- AB = 0 ⇒ A = 0 or B = 0
Practice Problems
- Solve x² + 3x − 10 = 0.
- Solve x² − 4x = 0.
Answers and Explanations
- Answer:x = 2, −5. (x − 2)(x + 5) = 0.
- Answer:x = 0, 4. x(x − 4) = 0.