题目内容
计算,能简算的要简算. 49.2÷(4.3×2-0.4) |
| ||||||||||||||||
9
|
(
|
分析:(1)先算括号内的乘法,再算括号内的减法,最后算出发;
(2)运用乘法分配律简算;
(3)运用加法交换律与结合律以及减法的性质简算;
(4)先算括号内的,再算括号外的除法,最后算减法.
(2)运用乘法分配律简算;
(3)运用加法交换律与结合律以及减法的性质简算;
(4)先算括号内的,再算括号外的除法,最后算减法.
解答:解:(1)49.2÷(4.3×2-0.4),
=49.2÷(8.6-0.4),
=49.2÷8.2,
=6;
(2)
×
+
×
,
=
×(
+
),
=
×2,
=
;
(3)9
-(
-
)-
,
=9
-
+
-
,
=(9
+
)-(
+
),
=10-1,
=9;
(4)(
+
)÷
+
,
=
×
+
,
=
+
,
=
.
=49.2÷(8.6-0.4),
=49.2÷8.2,
=6;
(2)
4 |
5 |
7 |
9 |
4 |
5 |
11 |
9 |
=
4 |
5 |
7 |
9 |
11 |
9 |
=
4 |
5 |
=
8 |
5 |
(3)9
9 |
20 |
5 |
8 |
11 |
20 |
3 |
8 |
=9
9 |
20 |
5 |
8 |
11 |
20 |
3 |
8 |
=(9
9 |
20 |
11 |
20 |
5 |
8 |
3 |
8 |
=10-1,
=9;
(4)(
2 |
5 |
1 |
3 |
4 |
5 |
3 |
4 |
=
11 |
15 |
5 |
4 |
3 |
4 |
=
11 |
12 |
3 |
4 |
=
5 |
3 |
点评:此题考查了小数、分数的四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算律简便计算.
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