作业帮谁能巧算1-1/2-1/6-1/12-1/20-1/30-1/42-1/56-1/72-1/90
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谁能巧算1-1/2-1/6-1/12-1/20-1/30-1/42-1/56-1/72-1/90
谁能巧算1-1/2-1/6-1/12-1/20-1/30-1/42-1/56-1/72-1/90
谁能巧算1-1/2-1/6-1/12-1/20-1/30-1/42-1/56-1/72-1/90
1-1/2-1/6-1/12-1/20-1/30-1/42-1/56-1/72-1/90
=1/(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
原式=1-1/2-(1/2-1/3)……-(1/9-1/10)=1-1/10=9/10
1/6=1/2-1/3
1/12=1/3-1/4
......
1/90=1/9-1/10
所以原式=1-1/2-(1/2-1/3)……-(1/9-1/10)=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.+1/380
2%1+6%1+12%1+20%1+30%1
1/2+1/6+1/12+1/20+1/30
1/2-1/6-1/12-1/20-...-1/110
1/2,-1/6,1/12,-1/20,1/30
2/1+6/1+12/1+24/1+48/1
1/2+1/6+1/12+1/20+.1/90
2/1+6/1+12/1+20/1+...+2450/1
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72
1+1/2+1/12+1/6+1/20+1/30+1/40+1/56
(1-1/2)+(1-1/6)+(1-1/12)+...+(1-1/110)=?
1+1/2+1/6+1/12+1/20+1/30.+1/901+1/2+1/6+1/12+1/20+1/30+.+1/90简便计算
1/2+1/6+1/12+...+1/4054182 等于多少?
1/2+1/6+1/12+...+1/56=快
1/2+1/6+1/12+1/20=
1/2+1/6+1/12+.1/9900