## Elementary Algebra

$1-49n^2$
Using $(a-b)(a+b)=a^2-b^2$, or the product of the sum and difference of like terms, the given expression, $(1+7n)(1-7n) ,$ is equivalent to \begin{array}{l}\require{cancel} (1)^2-(7n)^2 \\\\= 1-49n^2 .\end{array}