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1.9x9.9+0.19的简便运算

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1.9×9.9+0.19 =1.9×9.9+1.9×0.1 =1.9×(9.9+0.1) =1.9×10 =19

解:原式=1.9×(10-0.1)×0.19 =(1.9×10-1.9×0.1)×0.19 =(19-0.19)×0.19 =19×0.19-0.19×0.19 =3.61-0.0361 =3.5739

1.9×9.9+0.19 =1.9×9.9+1.9×0.1 =1.9×(9.9+0.1) =1.9×10 =19

解:原式=9.9+0.1+19.9+0.1+119.9+0.1=10+20+120=150 延伸:做这类题一般先从式子下手,找出其中通过一些变式之后可以得到化简以及合并的同类项,然后再进行变式以及化简。需要注意的是,这种题的结果一般是整数形式的,如果出现小数或分式,则...

19

原式 =4.6x0.19+0.54x1.9 =4.6x0.19+5.4x0.19 =(4.6+5.4)x0.19 =10x0.19 =1.9 或者 =0.46x1.9+0.54x1.9 =(0.46+0.54)x1.9 =1x1.9 =1.9

十九分之二加二十一分之一括号乘十九乘二十一用简便计算(2/19+1/21)*(19*21)=2/19*19*21+1/21*19*21=42+19=61

解原式=7/19*25*19*2/5 =7*5*2 =70

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