A2 June 2020 Paper 1 Q3
3 The quadratic equation \(ax^2 + bx + c = 0\) \((a, b, c \in \mathbb{R})\) has real roots \(\alpha\) and \(\beta\).
One of the four statements below is incorrect.
Which statement is incorrect?
Tick (✓) one box. [1 mark]
- \(c = 0 \Rightarrow \alpha = 0 \text{ or } \beta = 0\)
- \(c = a \Rightarrow \alpha \text{ is the reciprocal of } \beta\)
- \(b \lt 0 \text{ and } c \lt 0 \Rightarrow \alpha \gt 0 \text{ and } \beta \gt 0\)
- \(b = 0 \Rightarrow \alpha = -\beta\)
| Scheme | Marks | AO |
|---|---|---|
| Ticks \(b \lt 0 \text{ and } c \lt 0 \Rightarrow \alpha \gt 0 \text{ and } \beta \gt 0\) | B1 | 2.2a |
| (1 mark) |
Typical solution
\(b \lt 0 \text{ and } c \lt 0 \Rightarrow \alpha \gt 0 \text{ and } \beta \gt 0\)