This key facts covers The Discriminant: b² - 4ac within Quadratic Formula for GCSE Mathematics. Revise Quadratic Formula in Algebra for GCSE Mathematics with 11 exam-style questions and 5 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 6 of 8 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
The Discriminant: b² - 4ac
This tells you how many solutions exist:
| Value of b² - 4ac | What it means | Type of roots |
|---|---|---|
| Positive (> 0) | Two different real solutions | Graph crosses x-axis twice |
| Zero (= 0) | One repeated solution | Graph touches x-axis once |
| Negative (< 0) | No real solutions | Graph doesn't cross x-axis |
Practice questions for Quadratic Formula
For the equation 3x² − 5x + 2 = 0, what are the values of a, b, and c in the quadratic formula?
Explain what the value of the discriminant (b² − 4ac) tells you about the solutions to a quadratic equation.
Quick recall flashcards
The Quadratic Formula
x = (-b ± √(b² - 4ac)) / 2a
Quadratic Formula
x = (-b ± √(b²-4ac))/2a for ax² + bx + c = 0