Condition

If the coefficient of $x^2$ is 1, think of two numbers which:

1. Add to make the $b$
2. Multiply to make $c$

Otherwise, utilise the cross method.

Cross Method

1. Left side multiply to make $a$
2. Centre add to make $b$
3. Right side multiply to make $c$

Difference of two squares

• $a^2 - b^2 = (a+b)(a-b)$
• $(x^2 - 9) = (x+3)(x-3)$

Complete the square

Complete the square is just a different way of writing a quadratic. It allows for different things to be done.

Completing The Square