Factorising by inspection

Finding two numbers that do two jobs at once.

Two numbers, two jobs

To factorise x² + 5x + 6 you need two numbers that multiply to 6 and add to 5. Those two conditions almost always pin down a single pair.

x^{2} + 5 x + 6 = (x + 2) (x + 3)

2 and 3 multiply to 6 and add to 5.

Your turn

x^{2} + 5 x + 6 = 0

Solve x^2 + 5x + 6 = 0

Worked solution

x^{2} - 5 x + 6 = 0

Try it yourself first. Reveal the steps one at a time if you get stuck.

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