(1+1/5)*(1-1/9)*(1+1/6)*(1-1/6)*(1+1/7)*(1-1/7)*...*(1+1/20)
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(1+1/5)*(1-1/9)*(1+1/6)*(1-1/6)*(1+1/7)*(1-1/7)*...*(1+1/20)*(1-1/20)用简便算法怎样算?
(1+1/5)*(1-1/9)*(1+1/6)*(1-1/6)*(1+1/7)*(1-1/7)*...*(1+1/20)*(1-1/20)
题目就是(1+1/5)*(1-1/5)*(1+1/6)*(1-1/6)*(1+1/7)*(1-1/7)*...*(1+1/20)*(1-1/20)
=(1+1/5)*(1+1/6)*(1+1/7)*...*(1+1/20)*(1-1/5)*(1-1/6)*(1-1/7)*...*(1-1/20)
=(6/5)*(7/6)*(8/7)*...*(21/20)*(4/5)*(5/6)*(6/7)*...*(19/20)
=(21/5)*(4/20)
=21/25
题目就是(1+1/5)*(1-1/5)*(1+1/6)*(1-1/6)*(1+1/7)*(1-1/7)*...*(1+1/20)*(1-1/20)
=(1+1/5)*(1+1/6)*(1+1/7)*...*(1+1/20)*(1-1/5)*(1-1/6)*(1-1/7)*...*(1-1/20)
=(6/5)*(7/6)*(8/7)*...*(21/20)*(4/5)*(5/6)*(6/7)*...*(19/20)
=(21/5)*(4/20)
=21/25
(1+1/5)*(1-1/9)*(1+1/6)*(1-1/6)*(1+1/7)*(1-1/7)*...*(1+1/20)
(1+1/6)×(1+1/7)+(1+1/8)+(1+1/9)+(1+1/10)
(1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9+1/10+1/11+1/12+1/13+1/14+1/
1-1/2+1/3-1/4+1/5-1/6+1/7-1/8+1/9……+1/19-1/20=?
1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9+1/10等于多少?
(1+1/2)*(1+1/4)*(1+1/6)*(1+1/8)*(1+1/3)*(1+1/5)*(1+1/7)*(1+1
化简: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
(1+1/6)*(1+1/7)*(1+1/8)*(1+1/9)*(1+1/10)简便算法?
一道数学题.|1-1\2|+|1\2-1\3|+|1\3-1\4|+|1\5-1\6|+|1\7-1\8|+|1\9+1
计算题1-1/2-1/3+1/4+1/5-1/6-1/7+1/8+1/9……-1/2006-1/2007+1/2008+
数列计算 1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9=?
(1)1+1/2+1/3+1/4+1/5+1/6+1/7+1/14+1/28