Question 104678
{{{(3Y^2 + 1) (3Y^2 - 1)}}}
Use the FOIL method (First, Outer, Inner, Last)
First {{{(highlight(3Y^2) + 1) (highlight(3Y^2) + (-1))}}} : {{{3Y^2*3Y^2}}}
Outer {{{(highlight(3Y^2) + 1) (3Y^2 + highlight((- 1)))}}} : {{{3Y^2*(-1)}}}
Inner {{{(3Y^2 + highlight(1)) (highlight(3Y^2) +(-1))}}} : {{{(1)*3Y^2}}}
Last {{{(3Y^2 + highlight(1)) (3Y^2 + highlight((-1)))}}} {{{1*(-1)}}}

{{{(3Y^2 + 1) (3Y^2 - 1)}}}= {{{3Y^2*3Y^2+3Y^2*(-1)+(1)*3Y^2+1*(-1)}}}
{{{(3Y^2 + 1) (3Y^2 - 1)}}}= {{{9Y^4-cross(3Y^2)+cross(3Y^2)-1}}}
{{{(3Y^2 + 1) (3Y^2 - 1)}}}= {{{9Y^4-1}}}