题目内容
计算(怎样简便就怎样算)
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|
(
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[1-(
|
|
x+
|
分析:算式(1)可根据乘法交换律进行计算;
算式(2)(3)可根据乘法分配律进行计算;
算式(4)根据四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的;
算式(5)可根据比例的基本性质:比例中的两外项之积等于两内项之积,以及等式的基本性质:等式两边同时乘以,除以,加上、减去同一个数,等式仍然成立;
算式(5)根据等式的基本性质解方程即可.
算式(2)(3)可根据乘法分配律进行计算;
算式(4)根据四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的;
算式(5)可根据比例的基本性质:比例中的两外项之积等于两内项之积,以及等式的基本性质:等式两边同时乘以,除以,加上、减去同一个数,等式仍然成立;
算式(5)根据等式的基本性质解方程即可.
解答:解:(1)
×
÷
×
,
=
÷
×
×
,
=
;
(2)
×6.7+4.3×0.75-75%
=0.75×6.7+4.3×0.75-0.75,
=(6.7+4.3-1)×0.75,
=10×0.75,
=7.5;
(3)(
+
-
)×30
=
×30+
×30-
×30,
=21+25-24,
=22;
(4)[1-(
-
)] ×
=[1-(0.5-0.25)]×
,
=[1-0.25]×
,
=0.75×
,
=0.5;
(5)
:
=
:x
x=
×
x÷
=
×
÷
,
x=
;
(6)x+
x=60
x=60,
x÷
=60÷
x=48.
1 |
3 |
3 |
5 |
1 |
3 |
3 |
5 |
=
1 |
3 |
1 |
3 |
3 |
5 |
3 |
5 |
=
9 |
25 |
(2)
3 |
4 |
=0.75×6.7+4.3×0.75-0.75,
=(6.7+4.3-1)×0.75,
=10×0.75,
=7.5;
(3)(
7 |
10 |
5 |
6 |
4 |
5 |
=
7 |
10 |
5 |
6 |
4 |
5 |
=21+25-24,
=22;
(4)[1-(
1 |
2 |
1 |
4 |
2 |
3 |
=[1-(0.5-0.25)]×
2 |
3 |
=[1-0.25]×
2 |
3 |
=0.75×
2 |
3 |
=0.5;
(5)
1 |
4 |
1 |
6 |
1 |
8 |
1 |
4 |
1 |
6 |
1 |
8 |
1 |
4 |
1 |
4 |
1 |
6 |
1 |
8 |
1 |
4 |
x=
1 |
12 |
(6)x+
1 |
4 |
5 |
4 |
5 |
4 |
5 |
4 |
5 |
4 |
x=48.
点评:完成本题要细心分析式中数据的特点,然后选择合适的方法进行计算.
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