题目内容
[3.6-(+2.8×)]÷1.2
4÷[(+0.75)×1]
4.5÷[(5.7+9.38×-)×]
[+1×(2-1)÷]
解:(1)[3.6-(+2.8×)]÷1.2,
=[3.6-(+2.8×)]÷,
=[3.6-(+×)]×,
=[3.6-(+)]×,
=[3.6-(+)]×,
=[3.6-]×,
=3.6×-,
=3-,
=3-1,
=1;
(2)4÷[(+0.75)×1],
=÷[()×],
=÷[],
=,
=,
=3;
(3)4.5÷[(5.7+9.38×-)×],
=4.5÷[(5.7+9.38×-)×],
=4.5÷[(5.7+4.02-0.72)×],
=4.5÷[(9.72-0.72)×],
=4.5÷[9×],
=4.5÷,
=4.5×,
=10;
(4)[+1×(2-1)÷],
=[+×(21)×],
=+××,
=+,
=,
=,
=11.
分析:(1)先计算括号内部的,在计算括号外面的,数值较大,认真计算.
(2)、(3)先计算中括号内部的小括号,在计算中括号的,最后计算括号外面的.
(4)先计算中括号内部的再计算括号外面的,数值较大,认真计算.
点评:本题主要考查了分数的四则混合运算的顺序,同时考查了分数的计算能力.
=[3.6-(+2.8×)]÷,
=[3.6-(+×)]×,
=[3.6-(+)]×,
=[3.6-(+)]×,
=[3.6-]×,
=3.6×-,
=3-,
=3-1,
=1;
(2)4÷[(+0.75)×1],
=÷[()×],
=÷[],
=,
=,
=3;
(3)4.5÷[(5.7+9.38×-)×],
=4.5÷[(5.7+9.38×-)×],
=4.5÷[(5.7+4.02-0.72)×],
=4.5÷[(9.72-0.72)×],
=4.5÷[9×],
=4.5÷,
=4.5×,
=10;
(4)[+1×(2-1)÷],
=[+×(21)×],
=+××,
=+,
=,
=,
=11.
分析:(1)先计算括号内部的,在计算括号外面的,数值较大,认真计算.
(2)、(3)先计算中括号内部的小括号,在计算中括号的,最后计算括号外面的.
(4)先计算中括号内部的再计算括号外面的,数值较大,认真计算.
点评:本题主要考查了分数的四则混合运算的顺序,同时考查了分数的计算能力.
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