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Common factor

The first thing to try when factorising is to take out a common factor. The factor can be a number, a letter or both. Afterwards the parentheses should have no common factor left. You can check by substituting a value into the original expression and into the product: they should give the same number.

Symbols

Example

$6x^2 + 9x = 3x(2x + 3)$. For $x = 2$: $6\cdot 4 + 18 = 42$ and $3\cdot 2\cdot 7 = 42$.

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Part of Mathematics 1T: Factorisation and polynomial division.