Factorising quadratics
Learn the method, practise it, then try real exam questions.
ATeaching
Example 1
Factorise x² + 7x + 12
- 1Write double brackets, each starting with x
(x )(x ) - 2List the pairs that multiply to make 12 (the last number):
1 and 12
2 and 6
3 and 4 - 3Pick the pair that adds to make 7 (the middle number in front of the x):
3 and 4. - 4Write the numbers in the brackets after each x, using + for a positive number and − for a negative number.
(x + 3)(x + 4)
Example 2
Factorise x² − 5x − 14
- 1Write double brackets, each starting with x
(x )(x ) - 2List the pairs that multiply to make 14 (the last number):
1 and 14
2 and 7 - 3Pick the pair that adds to make −5 (the middle number in front of the x):
2 and −7. - 4Write the numbers in the brackets after each x, using + for a positive number and − for a negative number.
(x + 2)(x − 7)
BQuestion generator
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CWorksheet
Factorise quadratics
Each worksheet contains 12 questions on factorising quadratics.
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