Question 630913
{{{ 9x^4-25y^2 }}}
{{{ ( 3x^2 )^2 - ( 5y )^2 }}}
-----------
The rule is:
{{{ a^2 - b^2 = ( a - b )*( a + b ) }}}
-----------
{{{ ( 3x^2 )^2 - ( 5y )^2  = ( 3x^2 - 5y )*( 3x^2 + 5y ) }}}