题目内容
看谁算得准,能简算的要简算.
38
|
|
|
|
考点:分数的四则混合运算
专题:运算顺序及法则
分析:(1)把分数拆成“整数+分数”的形式,运用除法的性质简算简算.
(2)把小数化为分数,运用乘法分配律简算.
(3)先算小括号内的,再算中括号内的,最后算括号外的.
(4)把除法变为乘法,运用乘法分配律简算.
(2)把小数化为分数,运用乘法分配律简算.
(3)先算小括号内的,再算中括号内的,最后算括号外的.
(4)把除法变为乘法,运用乘法分配律简算.
解答:
解:(1)38
÷19
=(38+
)÷19
=38÷19+
÷19
=2+
×
=2+
=2
(2)
×
+0.75×
=
×
+
×
=
×(
+
)
=
×
=
(3)
÷[(
-
)×3]
=
÷[
×3]
=
÷
=
×2
=
(4)
×
+
÷
=
×
+
×
=(
+
)×
=
×
=
19 |
40 |
=(38+
19 |
40 |
=38÷19+
19 |
40 |
=2+
19 |
40 |
1 |
19 |
=2+
1 |
40 |
=2
1 |
40 |
(2)
3 |
4 |
2 |
9 |
5 |
9 |
=
3 |
4 |
2 |
9 |
3 |
4 |
5 |
9 |
=
3 |
4 |
2 |
9 |
5 |
9 |
=
3 |
4 |
7 |
9 |
=
7 |
12 |
(3)
7 |
20 |
5 |
6 |
2 |
3 |
=
7 |
20 |
1 |
6 |
=
7 |
20 |
1 |
2 |
=
7 |
20 |
=
7 |
10 |
(4)
1 |
7 |
5 |
12 |
5 |
12 |
7 |
5 |
=
1 |
7 |
5 |
12 |
5 |
12 |
5 |
7 |
=(
1 |
7 |
5 |
7 |
5 |
12 |
=
6 |
7 |
5 |
12 |
=
5 |
14 |
点评:此题考查了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定律简便计算.
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