n{n+1}{n+2}{n+3}+1是哪个数的平方,并说明理由
问题描述：
n{n+1}{n+2}{n+3}+1是哪个数的平方,并说明理由
答
=n(n+3)(n+1)(n+2)+1
=(n^2+3n)(n^2+3n+2)+1
=(n^2+3n)^2+2(n^2+3n)+1
=(n^2+3n+1)^2