1/1X4+1/4X7+1/7X10+...+1/100X103=1/3×(1-1/4)+1/3×(1/4-1/7)+1/3×(1/7-1/10)+...+1/3×(1/100-1/103)=1/3×(1-1/4+1/4-1/7+1/7-1/10+...+1/100-1/103)=1/3×(1-1/103)=1/3×102/103=34/103希望对您有所帮助如有问题，可以追问。谢谢您的采纳
