Quadratics
Null Factor Law

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​​

When the product of two or more numbers is zero, then at least one of them must equal zero for this to be true.
\[\mathrm{If} \quad A\cdot B=0 \quad \mathrm{then\ either} \quad A=0\quad \mathrm{or}\quad B=0\]