排列组合解方程C(n+1,n+3)=C(n-1,n-1)+C(n,n+1)+C(n-2,n)

排列组合解方程C(n+1,n+3)=C(n-1,n-1)+C(n,n+1)+C(n-2,n)
排列组合解方程C(n+1,n+3)=C(n-1,n-1)+C(n,n+1)+C(n-2,n)

排列组合解方程C(n+1,n+3)=C(n-1,n-1)+C(n,n+1)+C(n-2,n)
排列组合解方程C(n+1,n+3)=C(n-1,n+1)+C(n,n+1)+C(n-2,n)
C(2,n+3)/=C(2,n+1)+C(1,n+1)+C(2,n)
(n+3)(n+2)/2=(n+1)n/2+n+1+n(n-1)/2
n^2+5n+6=n^2+n+2n+2+n^2-n
化简得n^2-n-2=0
(n-2)(n+1)=0
n=2,n=-1(舍去)
原题无解,题目可能有点错,把一个n-1改为n+1