(1+0.23+0.34)*(0.23+0.34+0.65)-(1+0.23+0.34+0.65)*(0.23+0.34的简便算是多少
问题描述：
(1+0.23+0.34)*(0.23+0.34+0.65)-(1+0.23+0.34+0.65)*(0.23+0.34的简便算是多少
答
令A=0.23+0.34=0.57
式子=(1+A)*(A+0.65)-(1+A+0.65)*A
=A+A2+0.65A+0.65-A-A2-0.65A
=0.65
答
(1+0.23+0.34)*(0.23+0.34+0.65)-(1+0.23+0.34+0.65)*(0.23+0.34)
=(0.23+0.34+0.65)+(0.23+0.34)*(0.23+0.34+0.65)-(0.23+0.34)-(0.23+0.34)(0.23+0.34+0.65)
=0.65
答
1、这道题要用“假设法”来做.2、假设：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）……...