Factorising: common factor and trinomials
Answers are for parents and teachers.
1
Factorise 14x² − 21x.
7x(2x − 3).
2
Find 58 × 27 + 58 × 73 quickly.
58 × 100 = 5800.
3
Solve x² − 7x = 0.
x(x − 7) = 0, so x = 0 or x = 7.
4
Factorise x² + 2x − 15 and 3x² + 7x + 2.
(x + 5)(x − 3) and (3x + 1)(x + 2).
5
A rectangle has width w cm, length w + 4 cm and area 45 cm². Find w.
w² + 4w − 45 = 0, so (w + 9)(w − 5) = 0 and w = 5 cm (the length is 9 cm).