Exam-style question
Try this first
A quadratic has discriminant zero. What does this tell you about its graph?.
- A.B3: justify each step using the relevant algebra and functions rule
- B.Use any familiar GCSE calculation even if it ignores quadratic functions and their graphs
- C.Write only the final answer without showing the mathematical method
- D.Change the notation or restrictions to make the algebra look simpler
Model answer
What a good answer should say
- The correct answer is B3: justify each step using the relevant algebra and functions rule.
- A zero discriminant means the quadratic has one repeated real root, so the graph touches the x-axis at its turning point.
This answer is tied to the objective: B3 Work with quadratic functions and their graphs; use the discriminant including the conditions for real and repeated roots; complete the square; solve quadratic equations including solving quadratic equations in a function of the unknown..
Explanation
Why this works
Use the explanation to connect the worked answer back to B3 Work with quadratic functions and their graphs; use the discriminant including the conditions for real and repeated roots; complete the square; solve quadratic equations including solving quadratic equations in a function of the unknown..
The correct option, B3: justify each step using the relevant algebra and functions rule, is supported because the discriminant links algebraic root structure to graph behaviour. Zero discriminant means a repeated root, not an interval of values or an inequality region.
Maths method check
- Topic focus: Pure Mathematics.
- Question style: practice.
- Reasoning demand: understanding.
- Check the operation, notation, units, and final answer form against the question before moving on.
Common mistake
No common mistake is linked to this question yet.