Question 8886
Your first step in ANY factoring problem is to take out the common factors!  In this expression, each term is divisible by 7 and y^2, so take out a common factor of {{{7y^2}}}


{{{7x^2y^2 + 147xy^2 - 504y^2}}}

{{{7y^2(x^2 + 21x - 72) }}}
{{{7y^2(x _______)(x_______) }}}


The trinomial factors if you can find two numbers whose product is -72 and whose difference is 21.  Try 24 and -3


{{{7y^2(x^2 + 21x - 72) }}}

{{{ 7y^2(x+24)(x-3) }}}


R^2 at SCC