答:
(a平方+3b-3)(a平方+3b+1)-5
=(a²+3b-3)(a²+3b+1)-5
=(a²+3b)²+(a²+3b)-3(a²+3b)-3-5
=(a²+3b)²-2(a²+3b)-8
=(a²+3b-4)(a²+3b+2)