题目内容
脱式计算.(能简算的要简算)
| [
| 42×(
| ||||||||||||||||||
|
| 5×4×(
|
考点:分数的四则混合运算
专题:运算顺序及法则
分析:(1)把除法化成乘法,再进行约分计算即可;
(2)先算小括号里的减法,再算中括号里的减法,最后算括号外的除法;
(3)运用乘法的分配律进行简算;
(4)运用乘法的分配律进行简算;
(5)把除以6化成乘以
,再运用乘法的分配律进行简算;
(6)去括号.再运用乘法的交换律、结合律进行简算.
(2)先算小括号里的减法,再算中括号里的减法,最后算括号外的除法;
(3)运用乘法的分配律进行简算;
(4)运用乘法的分配律进行简算;
(5)把除以6化成乘以
| 1 |
| 6 |
(6)去括号.再运用乘法的交换律、结合律进行简算.
解答:
解:(1)
×
÷
=
×
×
=
=1;
(2)[
-(
-
)]÷
=[
-
)]÷
=
÷
=
;
(3)42×(
+
)
=42×
+42×
=35+18
=53;
(4)
×
+
×
=
×(
+
)
=
×5
=14;
(5)
×
+
÷6
=
×
+
×
=
×(
+
)
=
×1
=
;
(6)5×4×(
×
)
=5×4×
×
=5×
×4×
=(5×
)×(4×
)
=1×3
=3.
| 7 |
| 16 |
| 12 |
| 35 |
| 3 |
| 20 |
=
| 7 |
| 16 |
| 12 |
| 35 |
| 20 |
| 3 |
=
| 7×12×20 |
| 16×35×3 |
=1;
(2)[
| 7 |
| 8 |
| 5 |
| 16 |
| 1 |
| 4 |
| 26 |
| 27 |
=[
| 7 |
| 8 |
| 1 |
| 16 |
| 26 |
| 27 |
=
| 13 |
| 16 |
| 26 |
| 27 |
=
| 27 |
| 32 |
(3)42×(
| 5 |
| 6 |
| 3 |
| 7 |
=42×
| 5 |
| 6 |
| 3 |
| 7 |
=35+18
=53;
(4)
| 14 |
| 5 |
| 3 |
| 2 |
| 14 |
| 5 |
| 7 |
| 2 |
=
| 14 |
| 5 |
| 3 |
| 2 |
| 7 |
| 2 |
=
| 14 |
| 5 |
=14;
(5)
| 7 |
| 4 |
| 5 |
| 6 |
| 7 |
| 4 |
=
| 7 |
| 4 |
| 5 |
| 6 |
| 7 |
| 4 |
| 1 |
| 6 |
=
| 7 |
| 4 |
| 5 |
| 6 |
| 1 |
| 6 |
=
| 7 |
| 4 |
=
| 7 |
| 4 |
(6)5×4×(
| 1 |
| 5 |
| 3 |
| 4 |
=5×4×
| 1 |
| 5 |
| 3 |
| 4 |
=5×
| 1 |
| 5 |
| 3 |
| 4 |
=(5×
| 1 |
| 5 |
| 3 |
| 4 |
=1×3
=3.
点评:完成此类题目要注意分析式中数据的特点,然后运用合适的方法计算.
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