a(a+1)(a+2)(a+3)+1=(a²+3a+1 )的平方
a(a+1)(a+2)(a+3)+1
=[a(a+3)][(a+1)(a+2)]+1
=(a²+3a)(a²+3a+2)+1
=(a²+3a)²+2(a²+3a)+1
=(a²+3a+1)²
a(a+1)(a+2)(a+3)+1=(a²+3a+1 )的平方
a(a+1)(a+2)(a+3)+1
=[a(a+3)][(a+1)(a+2)]+1
=(a²+3a)(a²+3a+2)+1
=(a²+3a)²+2(a²+3a)+1
=(a²+3a+1)²