7.214.5+172.8=？？这道题如何简便运算呢？是简便运算啊

2024-11-30 14:10:04

推荐回答（3个）

回答1：

7.2*14.5+17*2.8
原式=7.2*15-7.2*0.5+2.8*15+2.8*2=（7.2+2.8）*15-3.6+5.6=150+2=152

回答2：

=14.5*7.2+17*2.8
=14.5*7.2+(14.5+2.5)*2.8
=14.5*7.2+14.5*2.8+2.5*2.8
=14.5*(7.2+2.8)+2.5*2+2.5*0.8
=145+5+2
=152

回答3：

7.2*14.5+17*2.8
=(10-2.8)*14.5+17*2.8
=145-2.8*14.5+17*2.8
=145+2.8*(17-14.5)
=145+2.8*2.5
=145+7*0.4*2.5
=145+7
=152