4MA0 Higher June 2014 Paper 4 Q15
15 Solve the simultaneous equations
\[\begin{aligned} 3x + 2y &= 7 \\ 4x - 3y &= 15 \end{aligned}\]Show clear algebraic working.
(4)
| Scheme | Marks |
|---|---|
| eg. \(12x + 8y = 28\) \(-\;\;12x - 9y = 45\) or eg. \(9x + 6y = 21\) \(+\;\;8x - 6y = 30\) | M1 |
| \(y = -1\) or \(x = 3\) | A1 |
| Substitution of their found value above into one of the equations | M1 |
| \(x = 3\); \(y = -1\) | A1 |
| (4 marks) |
Notes
M1: for coefficient of \(x\) or \(y\) the same and correct operation to eliminate selected (condone any one arithmetic error in multiplication) or
for correct rearrangement of one equation followed by correct substitution in the other
A1: cao dep on M1
M1: (dep on 1st M1) for substituting to find the other variable or
correct method of elimination to find second variable (as first M1)
A1: cao
Award 4 marks for correct values if at least first M1 scored