两道简单极限题~

11 |

2 | 2009-7-20 12:36:44 | 显示全部楼层 |阅读模式

lim[n/(n+2)]^n=lim[1-1/(n+2)]^[-(n+2)*(-1)-2]=lim{[1-1/(n+2)]^[-(n+2)*(-1)]}*[1-1/(n+2)]^-2=e^-1lim [sqrt(n^2+2n)-sqrt(n^2+1)]lim[sqrt(n^2+2n)-sqrt(n^2+1)]*[sqrt(n^2+2n)+sqrt(n^2+1)]/[sqrt(n^2+2n)+sqrt(n^2+1)]=lim [n^2+2n-(n^2+1)]/[sqrt(n^2+2n)+sqrt(n^2+1)]=lim 2n/[sqrt(n^2+2n)+sqrt(n^2+1)]=1 sqrt是开根的意思...

使用道具举报