The quadratic formula can be used to solve any quadratic equation but is best saved for when an equation cannot be factorised.

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The quadratic formula is used when solving a quadratic which cannot be factorised.

The quadratic formula is:

\[x = \frac{{ - b \pm \sqrt {{b^2} - 4ac} }}{{2a}}\]

where a, b and c are taken from:

\[a{x^2} + bx + c\]