（2009•中山市）脱式计算．①0.9÷[0.69÷(14+0.9)−(34÷0.45−125)]②[(3.7+5.4×41113)×(1÷1617−1.0625)]+(1047+237)−1.9③[559−(4−315)+(379−43)]×[7.6÷45+(3.6−1.2)×1.25]④[2.5−(413−256)]÷[(8−7.2)×23÷223]⑤[4141

Question

（2009•中山市）脱式计算．
①0.9÷[0.69÷((1)/(4)+0.9)−((3)/(4)÷0.45−1(2)/(5))]
②[(3.7+5.4×4(11)/(13))×(1÷(16)/(17)−1.0625)]+(10(4)/(7)+2(3)/(7))−1.9
③[5(5)/(9)−(4−3(1)/(5))+(3(7)/(9)−(4)/(3))]×[7.6÷(4)/(5)+(3.6−1.2)×1.25]
④[2.5−(4(1)/(3)−2(5)/(6))]÷[(8−7.2)×(2)/(3)÷2(2)/(3)]
⑤[4(14)/(15)−1(4)/(5)×(0.25+(5)/(12))]÷(0.75+4(7)/(12))．

Answer 1

①0.9÷[0.69÷((1)/(4)+0.9)−((3)/(4)÷0.45−1(2)/(5))]
=0.9÷[0.69÷(23)/(20)-（(5)/(3)-1(2)/(5)）]
=0.9÷[0.69÷(23)/(20)-(4)/(15)]
=0.9÷[0.6-(4)/(15)]
=0.9÷(1)/(3)
=2.7；

②[(3.7+5.4×4(11)/(13))×(1÷(16)/(17)−1.0625)]+(10(4)/(7)+2(3)/(7))−1.9
=[（3.7+26(11)/(65)）]×（1(1)/(16)-1.0625）+13-1.9
=29(113)/(130)×0+13-1.9
=13-1.9
=11.1；

③[5(5)/(9)−(4−3(1)/(5))+(3(7)/(9)−(4)/(3))]×[7.6÷(4)/(5)+(3.6−1.2)×1.25]
=[5(5)/(9)-(4)/(5)+2(4)/(9)]×[9.5+2.4×1.25]
=7(1)/(5)×[9.5+3]
=7(1)/(5)×12.5
=90；

④[2.5−(4(1)/(3)−2(5)/(6))]÷[(8−7.2)×(2)/(3)÷2(2)/(3)]
=[2.5-1.5]÷[0.8×(2)/(3)÷2(2)/(3)]
=1÷[(8)/(15)÷2

作业帮用户 2017-09-24

问题解析

（1）（2）按照先算小括号里面的第二级运算，再算小括号里面的第一级运算，然后算中括号里面，最后算括号外面的顺序解答，
（3）（5）按照先算小括号里面的，再算中括号里面的第二级运算，最后按照从左到右顺序算中括号里面的顺序解答，
（4）按照先算小括号里面的，再算中括号里面的顺序解答．

名师点评

本题考点：

整数、分数、小数、百分数四则混合运算．

考点点评：

本题主要考查学生依据四则运算计算方法正确进行计算的能力，关键是计算结果要准确．

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