Question

Factor: 81x^2-49

Answer 1

\[\LARGE 81=9^2 \quad \quad and \quad \quad 49=7^2\]
so...

\[\LARGE 9^2x^2-7^2=(9x)^2-7^2\]
now use this formula:
\[\LARGE a^2-b^2=(a-b)(a+b)\]
to get...
\[\LARGE (9x)^2-7^2=(9x-7)(9x+7)\]

Answer 2

This is the same kind of problem as before.