Higher June 2022 Paper 2 Q10
10 Solve the simultaneous equations
\[\begin{aligned} 7x + 3y &= 3 \\ 3x - y &= 7 \end{aligned}\]Show clear algebraic working.
(3)
| Scheme | Marks |
|---|---|
eg \((+)\;\begin{aligned} 7x + 3y &= 3 \\ 9x - 3y &= 21 \end{aligned}\) or \((-)\;\begin{aligned} 21x + 9y &= 9 \\ 21x - 7y &= 49 \end{aligned}\) or eg \(7x + 3(3x - 7) = 3\) or \(7\left(\dfrac{7 + y}{3}\right) + 3y = 3\) | M1 |
| If first M1 gained then they can substitute an incorrect value if from ‘correct’ method to gain this mark. | M1 |
| Working required Answer: \(x = 1.5\), \(y = -2.5\) | A1 |
| (3) | |
| (3 marks) |
Notes
M1: a correct method to eliminate \(x\) or \(y\) – multiplying one or both equations so that one variable can be eliminated (allow a total of one error in multiplication) and the correct operation to eliminate
or
for substitution of one variable into the other equation.
M1: dep on M1 for a correct method to calculate the value of other letter eg substitution or starting again with elimination
A1: oe dep on M1