题目内容
(2004?陆良县)用递等式计算.
(1)3000-144÷12×83
(2)1.8÷0.15-0.3×0.4
(3)
÷[1÷(
-
)]
(4)[4-(
-
)]×
.
(1)3000-144÷12×83
(2)1.8÷0.15-0.3×0.4
(3)
1 |
6 |
1 |
3 |
1 |
6 |
(4)[4-(
3 |
4 |
3 |
8 |
16 |
29 |
分析:(1)先算除法,再算乘法,最后算减法;
(2)同时运算除法和乘法,最后算减法;
(3)先小括号里面的减法,再算中括号里面的除法,最后算括号外的除法;
(4)先小括号里面的减法,再算中括号里面的减法,最后算括号外的乘法;
(2)同时运算除法和乘法,最后算减法;
(3)先小括号里面的减法,再算中括号里面的除法,最后算括号外的除法;
(4)先小括号里面的减法,再算中括号里面的减法,最后算括号外的乘法;
解答:解:(1)3000-144÷12×83,
=3000-12×83,
=3000-996,
=2004;
(2)1.8÷0.15-0.3×0.4,
=12-0.12,
=11.88;
(3)
÷[1÷(
-
)],
=
÷[1÷
],
=
÷6,
=
;
(4)[4-(
-
)]×
,
=[4-
]×
,
=
×
,
=2.
=3000-12×83,
=3000-996,
=2004;
(2)1.8÷0.15-0.3×0.4,
=12-0.12,
=11.88;
(3)
1 |
6 |
1 |
3 |
1 |
6 |
=
1 |
6 |
1 |
6 |
=
1 |
6 |
=
1 |
36 |
(4)[4-(
3 |
4 |
3 |
8 |
16 |
29 |
=[4-
3 |
8 |
16 |
29 |
=
29 |
8 |
16 |
29 |
=2.
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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