1/2x5+1/5x8+1/8x11+1/11x14+1/14x17+1/17x20

来源:学生作业帮助网 编辑:作业帮 时间:2024/04/28 00:38:39
1/2x5+1/5x8+1/8x11+1/11x14+1/14x17+1/17x20

1/2x5+1/5x8+1/8x11+1/11x14+1/14x17+1/17x20
1/2x5+1/5x8+1/8x11+1/11x14+1/14x17+1/17x20

1/2x5+1/5x8+1/8x11+1/11x14+1/14x17+1/17x20
"规律是1/2-1/5=3/(2*5)
1/5-1/8=3/(5*8)
1/8-1/11=3/(8*11)
看出规律没?
原式
=(1/2-1/5+1/5-1/8+1/8-1/11+1/11-1/14+1/14-1/17+1/17-1/20)/3
=(1/2-1/20)/3
=(10/20-1/20)/3
=3/20"