Question 23796
No acutally this is really simple. 

{{{(a+b)^4-(a-b)^4}}}
expand the polynomoials
{{{a^4+b^4-a^4+b^4}}}   -(-) -->+ (negative times a negative gives positive.)
Simplify --The {{{a^4}}} cancel out
Left with {{{2b^4}}}