题目内容
|
(
|
(
| ||||||||||||||||||
| 7.25×20%+2.75×20% |
|
3.57×[
|
分析:(1)把除以6化成乘
,运用乘法的分配律进行简算,
(2)运用乘法的分配律进行简算,
(3)先算小括号里的减法,再算括号外的除法,最后算加法,
(4)运用乘法的分配律进行简算,
(5)先同时计算出乘法和除法,再算加法,
(6)先算小括号里的减法,再算在括号里的除法,最后算括号外的乘法.
| 1 |
| 6 |
(2)运用乘法的分配律进行简算,
(3)先算小括号里的减法,再算括号外的除法,最后算加法,
(4)运用乘法的分配律进行简算,
(5)先同时计算出乘法和除法,再算加法,
(6)先算小括号里的减法,再算在括号里的除法,最后算括号外的乘法.
解答:解:(1)
÷6+
×
,
=
×
+
×
,
=(
+
)×
,
=1×
,
=
;
(2)(
+
)×42,
=
×42+
×42,
=9+10,
=19;
(3)(
-
)÷
+
,
=
÷
+
,
=1+
,
=1
;
(4)7.25×20%+2.75×20%,
=(7.25+2.75)×20%,
=10×20%,
=2;
(5)
×
+
÷
,
=
+2,
=2
;
(6)3.57×[
÷(2.6-
)],
=3.57×[
÷2],
=3.57×
,
=0.51.
| 5 |
| 11 |
| 1 |
| 6 |
| 6 |
| 11 |
=
| 5 |
| 11 |
| 1 |
| 6 |
| 1 |
| 6 |
| 6 |
| 11 |
=(
| 5 |
| 11 |
| 6 |
| 11 |
| 1 |
| 6 |
=1×
| 1 |
| 6 |
=
| 6 |
| 11 |
(2)(
| 3 |
| 14 |
| 5 |
| 21 |
=
| 3 |
| 14 |
| 5 |
| 21 |
=9+10,
=19;
(3)(
| 7 |
| 12 |
| 1 |
| 4 |
| 1 |
| 3 |
| 1 |
| 6 |
=
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 6 |
=1+
| 1 |
| 6 |
=1
| 1 |
| 6 |
(4)7.25×20%+2.75×20%,
=(7.25+2.75)×20%,
=10×20%,
=2;
(5)
| 4 |
| 5 |
| 3 |
| 8 |
| 5 |
| 6 |
| 5 |
| 12 |
=
| 3 |
| 10 |
=2
| 3 |
| 10 |
(6)3.57×[
| 2 |
| 7 |
| 3 |
| 5 |
=3.57×[
| 2 |
| 7 |
=3.57×
| 1 |
| 7 |
=0.51.
点评:考查了分数、小数四则混合运算的顺序,要灵活运用运算定律进行简算.
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