(1+0.12+0.23)×(0.12+0.23+0.34)-(1+0.12+0.23+0.34)×(0.12+0.23)=______.

问题描述:

(1+0.12+0.23)×(0.12+0.23+0.34)-(1+0.12+0.23+0.34)×(0.12+0.23)=______.

设0.12+0.23=x,0.12+0.23+0.34=y.则:(1+0.12+0.23)×(0.12+0.23+0.34)-(1+0.12+0.23+0.34)×(0.12+0.23)=(1+x)y-(1+y)x,=y+xy-x-xy,=y-x,=(0.12+0.23+0.34)-(0.12+0.23),=0.12-0.12+0.23-0.2...
答案解析:通过观察发现这个算式较长,数据较多,但括号中有重复的数据,因此可设0.12+0.23=x,0.12+0.23+0.34=y,算式就简化为:(1+x)y-(1+y)x由此将算式整理计算即可.
考试点:小数的巧算.


知识点:在完成此类包含数据较多且式中含有相同子算式的题目中,可通过用字母代替式中数据或算式将原算式简化后进行巧算.