1/2+1/6+1/20+1/30+1/42+1/56+1/72=怎么算简便?没有1/90.
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1/2+1/6+1/20+1/30+1/42+1/56+1/72=怎么算简便?没有1/90.1/2+1/6+1/20+1/30+1/42+1/56+1/72=怎么算简便?没有1/90.1/2+1/6+
1/2+1/6+1/20+1/30+1/42+1/56+1/72=怎么算简便?没有1/90.
1/2+1/6+1/20+1/30+1/42+1/56+1/72=怎么算简便?
没有1/90.
1/2+1/6+1/20+1/30+1/42+1/56+1/72=怎么算简便?没有1/90.
用拆项法
1/2+1/6+1/20+1/30+1/42+1/56+1/72
=1/(1*2)+1/(2*3)+1/(4*5)+1/(5*6)+1/(6*7)+1/(7*8)+1/(8*9)
=1-1/2+1/2-1/3+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9
=1-1/3+1/4-1/9
=7/12
不过照常规来说,应该有1/12这一项的,是不是少打了,反正方法是一样的,拆项相消.
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,-1/20,1/30
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
1/2+1/6+1/12+1/20+1/30+1/42+1/56 简算
1/2+1/6+1/12+1/20+1/30+1/42+1/56简算,
简便运算:1/2+1/6+1/12+1/20+1/30+1/42+1/56
1+1/2+1/6+1/12+1/20+1/30+1/42的简便计算
2/1+6/1+12/1+20/1+30/1+42/1+56/1=?
1/2 - 1/6 - 1/12 - 1/20 - 1/30 - 1/42 - 1/56怎么算
1/2+1/6+1/12+1/20+1/30+.1/380+1/420=
1+1/2+1/6+1/12+1/20+1/30+1/42=?
1/2+1/6+1/12+1/20+1/30+1/42+1/56
1/2-1/6-1/12-1/20-1/30-1/42-1/56等于多少
2/1+6/1+12/1+20/1+30/1+42/1+56/1=
1/2+1/6+1/12+1/20+1/30+...+1/9702+1/9900