Question

(1+0.23+0.34)*(0.23+0.34+0.65)-(1+0.23+0.34+0.65)*(0.23+0.34)

Answer 1

不用楼上那么麻烦！
设A=0.23+0.34
原式
=(1+A)*(A+0.65)-(1+A+0.65)*(A)
=A²+A+0.65A+0.65-A²-A-0.65A
=0.65

Answer 2

设：1+0.23+0.34=a； 0.23+0.34=b；

(1+0.23+0.34)*(0.23+0.34+0.65)-(1+0.23+0.34+0.65)*(0.23+0.34）
=a×（b＋0.65）－（a＋0.65）×b
=ab＋0.65a－ab－0.65b
=0.65×（a－b）…………因为：a=1+0.23+0.34；b=0.23+0.34
=0.65×（1+0.23+0.34－0.23－0.34）
=0.65×1
=0.65

Answer 3

(1+0.23+0.34)×(0.23+0.34+0.65)-(1+0.23+0.34+0.65)×(0.23+0.34)
这道题目把(1+0.23+0.34)设为A，(0.23+0.34)设为B。
那么原式变成:
A×(B+0.65)-(A+0.65)×B
=AB+0.65A-AB-0.65B
=0.65A-0.65B
=0.65×(A-B)
=0.65×1
=0.65
{因为A=1+0.23+0.34，B=0.23+0.34，那么A-B=1+0.23+0.34-0.23-0.34=1}

Answer 4

设0.23+0.34=x
0.23+0.34+0.65=y
(1+0.23+0.34)*(0.23+0.34+0.65)-(1+0.23+0.34+0.65)*(0.23+0.34)
=(1+x)y-(1+y)x
=y+xy-x-xy
=y-x
=0.65