(0.12+0.23+0.34)×(0.23+0.34+0.45)-(0.12+0.23+0.34+0.45)×(0.23+0.34)=_.
问题描述:
(0.12+0.23+0.34)×(0.23+0.34+0.45)-(0.12+0.23+0.34+0.45)×(0.23+0.34)=______.
答
假设A=0.12+0.23+0.34,B=0.23+0.34
原式=A×(B+0.45)-(A+0.45)×B,
=AB+0.45A-AB-0.45B,
=0.45×(A-B);
把A=0.12+0.23+0.34,与B=0.23+0.34代入上式得:
0.45×(0.12+0.23+0.34-0.23-0.34),
=0.45×0.12,
=0.054.