## Elementary Algebra

$x(x+5)(x-5)$
Factoring out the greatest common factor of x, the given expression, $x^3-25x ,$ is equivalent to \begin{array}{l}\require{cancel} x(x^2-25) .\end{array} Using $a^2-b^2=(a+b)(a-b)$, the completely factored form of the expression above is \begin{array}{l}\require{cancel} x(x+5)(x-5) .\end{array}