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 7 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 6 of 7
Practice
11 questions
Recall
5 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 |