如图
热心网友
因为 1/[(5n-4)(5n+1)]=(1/5)*{[1/(5n-4)]-[1/(5n+1)]}所以 原式=(1/5)*lim{(1-1/6)+(1/6-1/11)+...+[1/(5n-4)-1/(5n+1)]} (n-无穷) =(1/5)*lim[1-1/(5n+1)] (n-无穷) =1/5
热心网友
lim=1/5*[1-1/6+1/6-1/11+......+1/(5n-4)-1/(5n+1)]=lim 1/5*5n/(5n+1)x--∞=1/5
热心网友
lim ={1/5*[1-1/6+1/6-1/11+...+1/(5n-4)-1/(5n+1)]}x－∞（中括号内中间的项消去，只剩1，-1/（5n+1）两项]=lim {1/5*[1-1/（5n+1）]}x－∞=lim 1/5x－∞=1/5
热心网友
等于1