(1/11+1/20+1/31+1/40)*(1/21+1/30+1/41+1/50)-(1/11+1/21+1/31+1/41+1/51)*(1/21+1/31+1/41)=?
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(1/11+1/20+1/31+1/40)*(1/21+1/30+1/41+1/50)-(1/11+1/21+1/31+1/41+1/51)*(1/21+1/31+1/41)=?
(1/11+1/20+1/31+1/40)*(1/21+1/30+1/41+1/50)-(1/11+1/21+1/31+1/41+1/51)*(1/21+1/31+1/41)=?
(1/11+1/20+1/31+1/40)*(1/21+1/30+1/41+1/50)-(1/11+1/21+1/31+1/41+1/51)*(1/21+1/31+1/41)=?
题目错了吧?
题目是不是这样的:
(1/11+1/21+1/31+1/41)*(1/21+1/31+1/41+1/51)-(1/11+1/21+1/31+1/41+1/51)*(1/21+1/31+1/41)
令a=1/21+1/31+1/41
∴原式=(1/11+a)*(a+1/51)-(1/11+a+1/51)*a
=a/11+a²+1/11*51+a/51-a/11-a²-a/51
=1/561
(1/11+1/20+1/31+1/40)*(1/21+1/30+1/41+1/50)-(1/11+1/21+1/31+1/41+1/51)*(1/21+1/31+1/41)=?
1/11-11/31+2/11-12/31+3/11-13/31+.+10/1-20/31=?简算
1/11-11/31+2/11-12/31+3/11-13/31+.+10/1-20/31=?
1/11-11/31+2/11-12/31+3/11-13/31+.+10/11-20/31=
一、1/11-1/31+2/11-12/31+3/11-13/31+……+10/11-20/31二、1/(5*7)+1/(7*9)+1/(9*11)+1/(11*13)
1 11 31 4113 ()
1+10+11+20+21+30+31+40.2001+2010=?
1/11-11/31+2/11-12/31+3/11-13/31……+10/11-20/31= 用简便方法3分钟内 快
1/11-11/31+2/11-12/31+3/11-13/31+……+10/11-20/31(简便计算)好的,
求助(1/11)-(11/31)+(2/11)-(12/31)+(3/11)-(13/31)+……(10/11)-)+(20/31) 的简便运算
骆驼祥子1-10页 11-20 21-30 31-40 41-50……主要内容,好词好句,感想
11分之1减31分之11加11分之2减31分之31,加11分之10减31分之20简便算法
(1/17+1/19)*20;(1/24+1/29)*30;(1/31+1/37)*40;(1/40+1/47)*50中谁最大?
计算 (1/11+1/21+1/31+1/41)*(1/21+1/31+1/41+1/51)-(1/11+1/21+1/31+1/41+1/51)*(1/21+1/31+1/41)
(1/11+1/21+1/31+1/41)*(1/21+1/31+1/41+1/51)-(1/11+1/21+1/31+1/41+1/51)*(1/21+1/31+1/41)老师要方法啊.
(1/11+1/21+1/31++1/41)*(1/21+1/31++1/41+1/51)-(1/11+1/21+1/31+1/41+1/51)*(1/21+1/31+1/41)=?
1 /6×11+1/11×16+1/16×21+1/21×26+1/26×31+1/31×36 =
(1/11+1/21+1/31+1/41)*(1/21+1/31+1/41+1/51)-(1/11+1/21+1/31+1/41+/51)*(1/21+1/31+1/41)