Higher November 2020 Paper 1 Q16
16 A sequence of numbers is formed by the iterative process
\[u_{n+1} = \frac{4}{u_n - 1} \qquad u_1 = 9\]Work out the values of \(u_2\) and \(u_3\) [2 marks]
| Answer | Mark | Comments |
|---|---|---|
| 0.5 | B1 | oe |
| \(-8\) | B1ft | ft any value other than 1 |
Additional guidance
| If they show \(u_2 = \dfrac{4}{8}\) but simplify or convert it incorrectly, award B1 for the 1st mark, but do not award B1(ft) for the 2nd mark eg \(u_2 = \dfrac{4}{8} = \dfrac{1}{4}\), \(u_3 = \dfrac{4}{-0.75} = -\dfrac{16}{3}\) | B1B0 |
| 0.5 (oe) and \(-8\) worked out, with \(-8\) on the \(u_2\) answer line | B0B1 |
| Non-integer answers must be given as correct decimals or correct fractions with integer numerator and denominator If ft, award the 2nd mark for a correct fraction with integer numerator and denominator even if then incorrectly simplified or converted | |
| If the answer line for \(u_2\) is incorrect, do not award the 1st mark for \(10 = \dfrac{4}{8}\) in working |