Intermediate November 2021 Unit 2 Q10
10. A rectangle has sides of length \(2(3a - 7)\) cm and \((5a + 4)\) cm.
Diagram not drawn to scale
Form an expression, in terms of \(a\), for the perimeter of this rectangle.
You must simplify your expression. [3]
| Scheme | Marks | Comments |
|---|---|---|
| 4(3a – 7) + 2(5a + 4) or equivalent. | B1 | For a correct expression for the perimeter. |
| = 12a – 28 + 10a + 8 or equivalent. | B1 | For removal of brackets FT only from 2(3a – 7) + (5a +4) or equivalent OR 2(3a – 7) + 2(5a +4) or equivalent. |
| = 22a – 20 (cm) or 2(11a – 10) (cm) | B1 | For collection of terms FT if of equivalent difficulty. Mark final answer. |
Alternative approach
| Scheme | Marks | Comments |
|---|---|---|
| 2[2(3a −7) + (5a + 4)] | B1 | For a correct expression for the perimeter. |
| = 12a − 28 + 10a + 8 or 2( 6a – 14 + 5a +4) | B1 | For removal of brackets (within ‘square brackets’) FT only from 2 [2(3a – 7) + 2(5a +4)] or equivalent. |
| = 22a – 20 (cm) or 2(11a – 10) (cm) | B1 | For collection of terms FT only from 2 [2(3a – 7) + 2(5a +4)] or equivalent. FT if of equivalent difficulty. Mark final answer |