Module 5 · Answers
Answers & working
Workings shown so you can see where each answer comes from.
Section A — Easy
01
(a) 6a (b) 4x + 5y (c) 6x²
02
(a) 4x + 12 (b) 10y − 5 (c) −3a − 15 (d) x² + 6x
03
(a) 6(x + 2) (b) 5(2y − 5) (c) x(x + 5)
04
x = y − 7
05
31.4 cm
C = πd = 3.14 × 10.
06
50.24 cm²
A = πr² = 3.14 × 16.
Section B — Medium
07
5x + 10
3x + 12 + 2x − 2 = 5x + 10.
08
(a) 4(2a + 3b) (b) 3x(2x − 3) (c) 2x(2y + 3)
09
a = (v − u) / t
v − u = at, then divide by t.
10
14π cm
C = 2πr = 2π × 7 = 14π.
11
r = √50 = 5√2 ≈ 7.07 cm
πr² = 50π → r² = 50.
12
706.5 cm²
r = 15. A = 3.14 × 15² = 3.14 × 225 = 706.5.
Section C — Hard
13
4x − 7
10x − 15 − 6x + 8 = 4x − 7.
14
r = √(A / π)
Divide both sides by π, then take the square root.
15
44 cm
154 = (22/7) × r² ⇒ r² = 49 ⇒ r = 7.
C = 2 × (22/7) × 7 = 44.
C = 2 × (22/7) × 7 = 44.
16
30.8 cm
Half circumference + diameter.
= π × r + d
= 3.14 × 6 + 12 = 18.84 + 12 = 30.84.
= π × r + d
= 3.14 × 6 + 12 = 18.84 + 12 = 30.84.
17
17 cm
P/2 = l + w → l = P/2 − w = 25 − 8 = 17.