原式=a(2a²-7ab+3b²)
=a(2a-b)(a-3b)��д����ϸ��ллԭʽ=a(2a²-7ab+3b²)=a(2a²-ab-6ab+3b²)=a[a(2a-b)-3b(2a-b)]=a(2a-b)(a-3b)