# Edexcel IGCSE Maths 复习笔记 2.3.2 Expanding Two Brackets - Harder

Edexcel IGCSE Maths 复习笔记 2.3.2 Expanding Two Brackets - Harder

#### Hidden FOIL (aka spot the hidden brackets)

• Always write (a + b)2 as (a + b)(a + b)

#### Beware of minus signs

• Remember the basic rules:“ − × − = + ”

“ − × + = − ”

#### How to multiply out two brackets

• Write FOIL above your working spaceF – First term in each bracket

O – Outer pair of termsI – Inner pair of terms

L – Last term in each bracket

• Write down the four MULTIPLICATIONS

Careful here – you have to be sure to include any minus signs!

• Simplify by collecting LIKE TERMS (if there are any)

Worked Example