Changes

Since in many situations only the positive square root has any meaning, to be clear that both square roots are to be considered, in mathematics the convention is to use a sign, pronounced "plus or minus", in front of the square root symbol:

Since in many situations only the positive square root has any meaning, to be clear that both square roots are to be considered, in mathematics the convention is to use a sign, pronounced "plus or minus", in front of the square root symbol:

:<math>\pm sqrt{9} = \pm 3</math>

:<math>\pm \sqrt{9} = \pm 3</math>

This has important implications when solving equations, in that, if the square root of both sides is taken, one must be careful to allow for both the positive and negative square root.  A well known example is [[completing the square]] to solve a [[quadratic equation]].

This has important implications when solving equations, in that, if the square root of both sides is taken, one must be careful to allow for both the positive and negative square root.  A well known example is [[completing the square]] to solve a [[quadratic equation]].