Higher June 2025 Paper 3 Q17
17 Solve \(\dfrac{5x}{3x - 1} - \dfrac{2x}{3x + 1} = 1\) (3)
| Answer | Mark | Mark scheme |
|---|---|---|
| \(-\dfrac{1}{7}\) | M1 | for using a common denominator eg \(\dfrac{5x(3x + 1) - 2x(3x - 1)}{(3x - 1)(3x + 1)}\ (= 1)\) or for removing the fraction eg \(5x(3x + 1) - 2x(3x - 1) = (3x - 1)(3x + 1)\) |
| M1 | for correct methods to remove all fraction(s) and expand the brackets, eg \(15x^2 + 5x - 6x^2 + 2x = 9x^2 + 3x - 3x - 1\) | |
| A1 | for \(-\dfrac{1}{7}\) oe |
Additional guidance
Allow one error in total in all the expansions (may be a sign error)
Allow \(-0.14(2\ldots)\) for \(-\dfrac{1}{7}\)