谁能巧算1-1/2-1/6-1/12-1/20-1/30-1/42-1/56-1/72-1/90

来源：学生作业帮编辑：作业帮分类：数学作业时间：2024/07/14 20:58:03

1-1/2-1/6-1/12-1/20-1/30-1/42-1/56-1/72-1/90
=1/(1*1)-1/(1*2)-1/(2*3)-1/(3*4)-1/(4*5)-1/(5*6)-1/(6*7)-1/(7*8)-1/(8*9)-1/(9*10)
因为1/(x*y)=1/x-1/y
所以原式=1/1-1/2+1/2-1/3+1/3-1/4+...-1/10=1-1/10=9/10

谁能巧算1-1/2-1/6-1/12-1/20-1/30-1/42-1/56-1/72-1/90 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+.1/9900 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/10 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110 2/1+6/1+12/1+20/1+30/1+42/1+56/1+72/1+90/1等于多少 2\1-6\1-12\1-20\1-30\1-42\1-56\1-72\1-90\1 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90简便计算 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90简算 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90= 计算1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=多少