Factorising

Factorising

• Factorising is the opposite of expanding brackets
• You need to look for the largest factors you can take out of every term in the expression

Factorising x^2 + bx + c

• You need to write the expression with two brackets
• x^2 + 7x + 10
  • You need to find two numbers which add up to 7 and multiply to make 10
  • 5+2=7
  • 5x2=10
  • When factorising x^2 + bx + x use this table to help find the two numbers

Factorising ax^2 + bx + x

• One of the brackets must contain a ax term
• Try pairs of numbers which have a product of c
• Check each pair by multiplying out the brackets

Difference of two squares

• You can factorise expression that are written as something^2 - something else^2