Quadratics
Solution by Factorisation

Quadratics

Factorising when A = 0

• Sum and product method (part 1)
• Sum and product method (part 2)

Factorising when A ≠ 0

• Cross method (part 1)
• Cross method (part 2)

Factorising special situations​

• Factorising perfect squares
• Factorising difference of two squares (part 1)
• Factorising difference of two squares (part 2)
• ​Factorising by completing the square​

Solving quadratic equations

• Solving basic quadratics
• Null factor law
• Solution by factorisation
• Solution by completing the square
• The quadratic formula

Sketching quadratic equations

• From factorised form
• From vertex form (part 1)
• From vertex form (part 2)
• By completing the square​​

To solve quadratics in an unfactored form, first the expression must be factorised. Then the null factor law can be used to find the solution(s). When asked to solve a quadratic in factorised form, complete the following:
Step 1: If necessary, rearrange the equation so one side equals zero.
Step 2: Fully factorise the other side.
Step 3: Use the null factor law.
​Step 4: Solve the remaining linear equations.