简便运算题(1+1/2+1/3+1/4)*(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4)

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简便运算题(1+1/2+1/3+1/4)*(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4)

简便运算题(1+1/2+1/3+1/4)*(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4)
简便运算题(1+1/2+1/3+1/4)*(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4)

简便运算题(1+1/2+1/3+1/4)*(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4)
用A表示1/2+1/3+1/4
那么
原式=(1+A)*(A+1/5)-(1+A+1/5)*A
=1/5+6/5*A+A*A-A*A-6/5*A
=1/5

(1+1/2+1/3+1/4)*(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4)
=(1+1/2+1/3+1/4)*(1/2+1/3+1/4)+(1+1/2+1/3+1/4)*(1/5)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4)
=(-1/5)*(1/2+1/3+1/4)+(1+1/2+1/3+1/4)*(1/5)
=1/5

我来回答!
为了方便起见,
假设A=(1+1/2+1/3+1/4+1/5), B=(1/2+1/3+1/4+1/5)
那么很明显:A-B=1
如此,原题= (A-1/5)* B -A*(B-1/5)
= A*B - 1/5*B - A*B +1/5 *A
= 1/5*(A-B)
= 1/5
哈哈
不知道小弟弟/妹妹有没有学过代数.不管啦.

简便运算题
(1+1/2+1/3+1/4)*(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4)
=(1+1/2+1/3+1/4+1/5)*[(1+1/2+1/3+1/4)-(1/2+1/3+1/4)]-(1+1/2+1/3+1/4)
=(1+1/2+1/3+1/4+1/5)*1-(1+1/2+1/3+1/4)
=1/5