∵X的N+1次方加（X+1）的2N-1次方
=(x+1)^(2N)/(x+1)+x^(N+1)
=[(x^2+2x+1)^N+(x+1)*x^(N+1)]/(x+1)
={[(x^2+x+1)+x]^n+(x+1)*x*x^N}/(x+1)
=[(x^2+x+1)^n+nx(x^2+x+1)^(n-1)+.+n(x^2+x+1)*x^(n-1)+x^n+(x^2+x)*x^n]/(x+1)
=[(x^2+x+1)^n+nx(x^2+x+1)^(n-1)+.+n(x^2+x+1)*x^(n-1)+(x^2+x+1)*x^n]/(x+1)
分子每一项都有x^2+x+1
∴能被X^2+x+1整除