题目内容
(1)
×
+
÷
-1÷4
(2)76×(
-
)+23×(
+
)-53×(
-
)
| 11 |
| 7 |
| 1 |
| 4 |
| 1 |
| 4 |
| 7 |
| 10 |
(2)76×(
| 1 |
| 23 |
| 1 |
| 53 |
| 1 |
| 53 |
| 1 |
| 76 |
| 1 |
| 23 |
| 1 |
| 76 |
分析:(1)先把除法变成乘法或者分数,再运用乘法分配律简算;
(2)把算式分成三部分,分别运用乘法分配律简算,然后再运用加法结合律简算;注意增加后去括号时符号的变化.
(2)把算式分成三部分,分别运用乘法分配律简算,然后再运用加法结合律简算;注意增加后去括号时符号的变化.
解答:解:(1)
×
+
÷
-1÷4,
=
×
+
×
-
,
=
×(
+
-1),
=
×2,
=
;
(2)76×(
-
)+23×(
+
)-53×(
-
),
=76×
-
×76+23×
+
×23-53×
+
×53,
=
-
+
+
-
+
,
=(
-
)+(
+
)-(
-
),
=1+1-1,
=1.
| 11 |
| 7 |
| 1 |
| 4 |
| 1 |
| 4 |
| 7 |
| 10 |
=
| 11 |
| 7 |
| 1 |
| 4 |
| 1 |
| 4 |
| 10 |
| 7 |
| 1 |
| 4 |
=
| 1 |
| 4 |
| 11 |
| 7 |
| 10 |
| 7 |
=
| 1 |
| 4 |
=
| 1 |
| 2 |
(2)76×(
| 1 |
| 23 |
| 1 |
| 53 |
| 1 |
| 53 |
| 1 |
| 76 |
| 1 |
| 23 |
| 1 |
| 76 |
=76×
| 1 |
| 23 |
| 1 |
| 53 |
| 1 |
| 53 |
| 1 |
| 76 |
| 1 |
| 23 |
| 1 |
| 76 |
=
| 76 |
| 23 |
| 76 |
| 53 |
| 23 |
| 53 |
| 23 |
| 76 |
| 53 |
| 23 |
| 53 |
| 76 |
=(
| 76 |
| 23 |
| 53 |
| 23 |
| 23 |
| 76 |
| 53 |
| 76 |
| 76 |
| 53 |
| 23 |
| 53 |
=1+1-1,
=1.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
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