一道数学题:1/20+1/30+1/42+1/56.
2个回答
原式=1/(4×5)+1/(5×6)+1/(6×7)+1/(7×8)
=1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8
=1/4-1/8
=1/8
相关问题
一道要用简便方法的计算题,1\20+1\30+1\42+1\56
一道小学分数题1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=?
1/20+1/30+1/42+1/56+1/72+1/90
简算1/12+1/20+1/30+1/42+1/56
简便计算:[1/20]+[1/30]+[1/42]+[1/56]+[1/72].
数学题1/2+1/6+1/12+1/20+1/30+1/42
1/6+1/12+1/20+1/30+1/42+1/56=多少
数学探索规律2/1+6/1+12/1+20/1+30/1+42/1+56/1+72/1+90/1=?
2-(1/20+1/30+1/42+1/56+1/72)*8这道题如何简便计算?
1/20+1/30+1/42+1/56+1/72等于多少 简便