Exam-style question
Try this first
Which statement correctly interprets the discriminant of a quadratic equation?.
- A.B3: check notation, restrictions and final form
- 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: check notation, restrictions and final form.
- The discriminant b^2 - 4ac must be interpreted according to its sign: positive gives two real roots, zero gives one repeated real root, and negative gives no real roots.
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: check notation, restrictions and final form, is supported because discriminant reasoning depends on reading the sign of b^2 - 4ac accurately. This is a different skill from completing the square or sketching the graph.
The distractors are weaker because they confuse the algebraic test with a generic solving method.
Maths method check
- Topic focus: Pure Mathematics.
- Question style: practice.
- Reasoning demand: application.
- 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.