1/2+1/6+1/12+.+1/72+1/90等于多少1/2+1/6+1/12+.+1/72+1/90答案是多少
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1/2+1/6+1/12+.+1/72+1/90等于多少
1/2+1/6+1/12+.+1/72+1/90答案是多少
您好!
1/2+1/6+1/12+.+1/90
=1/1*2+1/2*3+.+1/9*10
=(1/1-1/2)+(1/2-1/3)+.+(1/9-1/10)
中间正负抵消
=1-1/10
=9/10
1/2+1/6+1/12+......+1/72+1/90
=1-1/2+1/2-1/3+1/3-1/4+...+1/8-1/9+1/9-1/10
=9/10=0.9
因为:裂项公式:1/n(n+1)=1/n-1/(n+1)
所以:1/2+1/6+1/12+......+1/90
=1/1*2+1/2*3+......+1/9*10
=(1/1-1/2)+(1/2-1/3)+......+(1/9-1/10) (中间正负抵消)
=1-1/10
=9/10
记住公式,同类题可解。
1/1*2 + 1/2*3 +1/3*4 +.....+1/9*10 =1/1 +1/2 -1/2 +1/3 -1/3+....+1/9 -1/9 +1/10=1+1/10=1/11
裂项公式:1/n(n+1)=1/n-1/(n+1)
所以:1/2+1/6+1/12+......+1/90
=1/1*2+1/2*3+......+1/9*10
=(1/1-1/2)+(1/2-1/3)+......+(1/9-1/10) (中间正负抵消)
=1-1/10
=9/10
记住公式.
1/2+1/6+1/12+...+1/72简便运算
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+1/6+1/12+1/20+.+1/72+1/90
1-1/2+1/6+1/12+1/20+...+1/72+1/90
1/2+1/6+1/12+.+1/72+1/90等于多少1/2+1/6+1/12+.+1/72+1/90答案是多少
计算:1除以括号1/2+1/6+1/12+1/20+...1/72等于几
1/2+1/6+1/12+1/20+.+1/72+1/90简算
1/2+1/6+1/12+1/20+…+1/72+1/90简算
计算:-1/2-1/6-1/12-1/20……-1/72-1/90
1/2+1/6+1/12+1/20+1/30+.+1/72
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+1/110
1+1/2+1/6+1/12+1/20+1/30+1/42+1/52+1/72=?更正: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+1/90=
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+190+1/110=?
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的答案,