4MA0 Higher June 2011 Paper 3 Q13
13 Solve \(\dfrac{2x - 1}{4} + \dfrac{x - 1}{5} = 2\)
(4)
| Scheme | Marks |
|---|---|
\(\dfrac{20(2x - 1)}{4} + \dfrac{20(x - 1)}{5} = 2 \times 20\) or \(5(2x - 1) + 4(x - 1) = 40\) or \(\dfrac{5(2x - 1) + 4(x - 1)}{20} = 2\) or \(\dfrac{5(2x - 1)}{20} + \dfrac{4(x - 1)}{20} = 2\) | M1 |
\(10x - 5 + 4x - 4 = 40\) or \(\dfrac{10x - 5 + 4x - 4}{20} = 2\) or \(\dfrac{10x - 5}{20} + \dfrac{4x - 4}{20} = 2\) | B1 |
| \(14x = 49\) or \(14x - 9 = 40\) or \(10x + 4x - 9 = 40\) or \(14x - 49 = 0\) | B1 |
| 3.5 | A1 |
| (Total 4 marks) |
Notes
M1: for clear intention to multiply both sides by 20 or a multiple of 20 or to express LHS as a single fraction with a denominator of 20 or a multiple of 20 or to express LHS as the sum of two fractions with denominators of 20 or a multiple of 20
May be implied by first B1
B1: expanding brackets (dep on M1)
B1: dep on both preceding marks
ie for a correct rearrangement of a correct equation
A1: dep on all preceding marks