Home > Subjects > Mathematics > Level 2 > 2.1 Algebra (AS90284) > Subject content > Expanding three brackets
- Subject: Mathematics
- AS: AS90284
- Level: 2
- Credits: 4
- External
Mathematics 2.1 Manipulate algebraic expressions and solve equations
Expanding three brackets
Example
(x + 5)(x + 2)(x – 3)
= (x + 5)(x2 – 3x + 2x – 6) Multiply out the second pair
of brackets
= (x + 5)(x2 – x – 6) –3x + 2x = –x
= x3 – x2 – 6x + 5x2 – 5x – 30 Multiply all terms in second
bracket by x and then everything
in second bracket by 5
= x3 + 4x2 – 11x – 30 Add the x2 terms together:
– x2 + 5x2 = 4x2
and the x terms together:
– 6x – 5x = –11x
