Factorise Quadratics

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Factorising Quadratics

Follow these steps to factorise an expression of the form ax² + bx + c where a is not 1. We use 2x² + 10x + 8 as an example.

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Step 1

  • Work out the initial set of brackets. The coefficients of x must multiply to give a (a = 2 in this example).
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Step 2

  • Find pairs of numbers that multiply to give c (8 in this case).
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Step 3

  • Trial and error until you find a combination that works.
  • Try each pair both ways round (e.g. 2 in the 2x bracket or in the x bracket) and with different signs until you find a combination that results in the correct x coefficient in the expansion.
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Step 4

  • Always expand to check your answer works.

Jump to other topics


1.1Place Value

1.2Factors & Multiples


1.4Fractions, Decimals & Percentages

1.5Growth & Decay

1.6Measurements & Units



3Ratio, Proportion & Rates of Change

4Geometry & Measures



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