4MA0 Higher June 2017 Paper 3R Q16
16 Make \(x\) the subject of the formula \(\quad y = \dfrac{ax + b}{cx + d}\)
(4)
| Scheme | Marks |
|---|---|
| \(cxy + dy = ax + b\) | M1 |
| e.g. \(cxy - ax = b - dy\) or \(dy - b = ax - cxy\) | M1 |
| \(x(cy - a) = b - dy\) | M1 |
| \(x = \dfrac{b - dy}{cy - a}\) | A1 |
| (4) | |
| (4 marks) |
Notes
M1: both terms in original denominator multiplied by \(y\)
M1: for isolating terms in \(x\) and non \(x\) terms correctly
ft from \(cxy + d = ax + b\) or \(cx + dy = ax + b\)
M1: for taking out a factor of \(x\) correctly provided there are two terms in \(x\)
A1: for \(x = \dfrac{b - dy}{cy - a}\) oe e.g. \(x = \dfrac{dy - b}{a - cy}\)