题目内容
(2008?陆良县)用递等式计算.
(1)2184-[(44×19+44)÷5]
(2)(2.5-2.5×0.6)÷0.25
(3)(
+
)÷
+
(4)
÷[(
+
)×
].
(1)2184-[(44×19+44)÷5]
(2)(2.5-2.5×0.6)÷0.25
(3)(
4 |
5 |
1 |
4 |
7 |
5 |
5 |
6 |
(4)
1 |
5 |
2 |
3 |
1 |
5 |
1 |
13 |
分析:(1)先把小括号里面的计算运用乘法分配律简算,再算中括号里面的除法,最后算括号外的减法;
(2)先把小括号里面的计算运用乘法分配律简算,再算括号外的除法;
(3)先算小括号里面的加法,再算括号外的除法,最后算括号外的加法;
(4)先算小括号里面的加法,再算中括号里面的乘法,最后算括号外的除法.
(2)先把小括号里面的计算运用乘法分配律简算,再算括号外的除法;
(3)先算小括号里面的加法,再算括号外的除法,最后算括号外的加法;
(4)先算小括号里面的加法,再算中括号里面的乘法,最后算括号外的除法.
解答:解:(1)2184-[(44×19+44)÷5],
=2184-[(19+1)×44÷5],
=2184-[20×44÷5],
=2184-[880÷5],
=2184-176,
=2008;
(2)(2.5-2.5×0.6)÷0.25,
=[2.5×(1-0.6)]÷0.25,
=[2.5×0.4]÷0.25,
=1÷0.25,
=4;
(3)(
+
)÷
+
,
=
×
+
,
=
+
,
=
;
(4)
÷[(
+
)×
],
=
÷[
×
],
=
÷
,
=3.
=2184-[(19+1)×44÷5],
=2184-[20×44÷5],
=2184-[880÷5],
=2184-176,
=2008;
(2)(2.5-2.5×0.6)÷0.25,
=[2.5×(1-0.6)]÷0.25,
=[2.5×0.4]÷0.25,
=1÷0.25,
=4;
(3)(
4 |
5 |
1 |
4 |
7 |
5 |
5 |
6 |
=
21 |
20 |
5 |
7 |
5 |
6 |
=
3 |
4 |
5 |
6 |
=
19 |
12 |
(4)
1 |
5 |
2 |
3 |
1 |
5 |
1 |
13 |
=
1 |
5 |
13 |
15 |
1 |
13 |
=
1 |
5 |
1 |
15 |
=3.
点评:1.一个算式里,如果含有两级运算,要先做第二级运算,后做第一级运算.
2.一个算式里,如果有括号,要先算小括号里的,再算中括号里面的.
2.一个算式里,如果有括号,要先算小括号里的,再算中括号里面的.
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