题目内容
计算(能简算的要简算).
|
|
(
|
分析:(1)先算小括号里面的减法,再算括号外的除法,最后算乘法;
(2)先把百分数化成分数,再运用乘法分配律简算;
(3)先运用乘法分配律简算,再用加法结合律简算.
(2)先把百分数化成分数,再运用乘法分配律简算;
(3)先运用乘法分配律简算,再用加法结合律简算.
解答:解:(1)
÷(1-
)×
,
=
÷
×
,
=
×
×
,
=
×
,
=
;
(2)
×
+80%×
,
=
×
+
×
,
=
×(
+
),
=
×1,
=
;
(3)(
+
)×
+
,
=
×
+
×
+
,
=
+
+
,
=(
+
)+
,
=1+
,
=1
.
| 5 |
| 6 |
| 9 |
| 20 |
| 5 |
| 9 |
=
| 5 |
| 6 |
| 11 |
| 20 |
| 5 |
| 9 |
=
| 5 |
| 6 |
| 20 |
| 11 |
| 5 |
| 9 |
=
| 50 |
| 33 |
| 5 |
| 9 |
=
| 250 |
| 297 |
(2)
| 4 |
| 5 |
| 6 |
| 11 |
| 5 |
| 11 |
=
| 4 |
| 5 |
| 6 |
| 11 |
| 4 |
| 5 |
| 5 |
| 11 |
=
| 4 |
| 5 |
| 6 |
| 11 |
| 5 |
| 11 |
=
| 4 |
| 5 |
=
| 4 |
| 5 |
(3)(
| 16 |
| 19 |
| 24 |
| 17 |
| 1 |
| 8 |
| 17 |
| 19 |
=
| 16 |
| 19 |
| 1 |
| 8 |
| 24 |
| 17 |
| 1 |
| 8 |
| 17 |
| 19 |
=
| 2 |
| 19 |
| 3 |
| 17 |
| 17 |
| 19 |
=(
| 2 |
| 19 |
| 17 |
| 19 |
| 3 |
| 17 |
=1+
| 3 |
| 17 |
=1
| 3 |
| 17 |
点评:运算定律是常用的简便运算的方法,要熟练掌握,灵活运用.
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