Question 47391
(a-b)(a+b) [Use FOIL to multiply]
{{{(a^2-b^2)}}}[When multiplying the difference of two squares, the middle term cancels.  The first and last terms are squared and the operation is subtraction (that is, difference)]
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For example:
{{{(x^2 - 25)}}} = {{{(x^2 - 5^2)}}} [The difference of two squares x and 5]
(x-5)(x+5) [No math involved, just plug-in the values that represent "a" and "b"]