Expanding Triple Brackets (Edexcel IGCSE Maths A (Modular))

Expanding Three Brackets

How do I expand three brackets?

• Multiply out any two of the brackets using a standard method and simplify

• Then multiply the resulting expression by the third (unused) bracket

• This step often looks like (x + a)(x² + bx + c)

• Every term in the first bracket must be multiplied with every term in the second bracket

• A grid can help to keep track of all the terms

  • E.g. (x + 2)(x² + 3x + 1)

    	x2	+3x	+1
    x	x3	3x2	x
    +2	2x2	6x	2

• Add all the terms inside the grid together

  • x³ + 2x² + 3x² + 6x + x + 2

• Simplify by collecting any like terms

  • x³ + 5x² + 7x + 2