Intermediate November 2020 Unit 2 Q6
6.
(a) Solve \(5(2x + 3) = 20\). [3]
(b) Factorise \(7a + 21\). [1]
(c) A number machine is shown below.
Write down an expression for the OUTPUT when the INPUT is \(n\). [2]
| Scheme | Marks | Comments |
|---|---|---|
| 10x + 15 = 20 OR 2x + 3 = 4 | B1 | FT until 2nd error. |
| 10x = 5 OR 2x = 1 | B1 | |
| x = \(\dfrac{5}{10}\) OR x = \(\dfrac{1}{2}\) or equivalent | B1 | Mark final answer. Allow an embedded answer but penalise −1 if contradicted by x ≠ ½ or 0·5. |
| Scheme | Marks | Comments |
|---|---|---|
| 7(a + 3) | B1 | Allow 7(1a + 3) Mark final answer. |
| Scheme | Marks | Comments |
|---|---|---|
| 5(n − 3) or 5×( n − 3) or (n − 3)5 or (n − 3) × 5 or 5n − 15 | B2 | B1 for sight of n − 3 × 5 OR sight of 5 × n − 3. B0 for unsupported n − 15 OR unsupported 5n − 3. Allow ‘n = 5(n – 3)’ etc Mark final answer. |