(1)a2-b2=(a+b)(a-b);
(2)①依题意可得:a2-b2=12
∴a2-b2=(a+b)(a-b)=12
∵a-b=3∴a+b=4;
②原式=(2-1)(2+1)(22+1)(24+1)(28+1)(216+1)(232+1)+1
=(22-1)(22+1)(24+1)(28+1)(216+1)(232+1)+1
=(24-1)(24+1)(28+1)(216+1)(232+1)+1
=(28-1)(28+1)(216+1)(232+1)+1
=(216-1)(216+1)(232+1)+1
=(232-1)(232+1)+1
=264-1+1
=264.