Pre-U Pre-U 9794/2 2012 Specimen — Question 3 6 marks

Exam BoardPre-U
ModulePre-U 9794/2 (Pre-U Mathematics Paper 2)
Year2012
SessionSpecimen
Marks6
TopicSimultaneous equations
TypeSimultaneous with substitution elimination
DifficultyStandard +0.3 This is a straightforward simultaneous equations problem requiring substitution of y = 1 - x into the quadratic equation, leading to a standard quadratic to solve. While it involves algebraic manipulation across multiple steps, the technique is routine and commonly practiced, making it slightly easier than average for A-level.
Spec1.02c Simultaneous equations: two variables by elimination and substitution

3 Solve the simultaneous equations $$x + y = 1 , \quad x ^ { 2 } - x y + y ^ { 2 } = 7 .$$

- Substitute for \(y\) [M1]
- Obtain quadratic equation in \(x\) [A1]
- Solve their quadratic equation [M1]
- Obtain \(x = 2\) and \(-1\) [A1]
- Substitute back to find \(y\) or \(x\), into linear or quadratic equation [M1]
- Obtain \(y = -1\) and \(2\) [A1ft]
Total: 6 marks
- Substitute for $y$ [M1]
- Obtain quadratic equation in $x$ [A1]
- Solve their quadratic equation [M1]
- Obtain $x = 2$ and $-1$ [A1]
- Substitute back to find $y$ or $x$, into linear or quadratic equation [M1]
- Obtain $y = -1$ and $2$ [A1ft]

**Total: 6 marks**
3 Solve the simultaneous equations

$$x + y = 1 , \quad x ^ { 2 } - x y + y ^ { 2 } = 7 .$$

\hfill \mbox{\textit{Pre-U Pre-U 9794/2 2012 Q3 [6]}}