n^2-(n-1)^2=2*n-1 理由是：n^2-(n-1)^2=[n-(n-1)]*[n+(n-1)]=2*n-1,2,n^2-(n-1)^2=2*n-1 理由是：n^2-(n-1)^2=[n-(n-1)]*[n+(n-1)]=2*n-1,2,n^2-(n-1)^2=2n-1,0,观察下列等式：1^2-0^2=1,2^2-1^2=3,3^2-2^2=5,4^2-3^2=7…… 则第n个等式可表示为：
