题目内容
能简算的要简算.
(
+
-
)×12
23-
×
÷
÷7+
×
5÷[(
+
)×
]
×23+
×67
(
-
)×
÷
.
(
| 1 |
| 6 |
| 3 |
| 4 |
| 2 |
| 3 |
23-
| 8 |
| 9 |
| 3 |
| 4 |
| 1 |
| 27 |
| 8 |
| 13 |
| 1 |
| 7 |
| 6 |
| 13 |
5÷[(
| 2 |
| 3 |
| 1 |
| 5 |
| 1 |
| 13 |
| 4 |
| 25 |
| 4 |
| 25 |
(
| 1 |
| 2 |
| 1 |
| 6 |
| 3 |
| 5 |
| 1 |
| 5 |
考点:分数的四则混合运算
专题:运算顺序及法则
分析:(1)(3)(5)利用乘法分配律简算;
(2)先算乘法,再算除法,最后算减法;
(4)先算加法,再算乘法,最后算除法;
(6)先算减法,再算乘法,最后算除法.
(2)先算乘法,再算除法,最后算减法;
(4)先算加法,再算乘法,最后算除法;
(6)先算减法,再算乘法,最后算除法.
解答:
解:(1)(
+
-
)×12
=
×12+
×12-
×12
=2+9-8
=3;
(2)23-
×
÷
=23-
×27
=23-18
=5;
(3)
÷7+
×
=
×
+
×
=(
+
)×
=
×
=
;
(4)5÷[(
+
)×
]
=5÷(
×
)
=5÷
=5×15
=75;
(5)
×23+
×67
=
×(23+67)
=
×90
=
;
(6)(
-
)×
÷
=(
-
)×
÷
=
×
×5
=1.
| 1 |
| 6 |
| 3 |
| 4 |
| 2 |
| 3 |
=
| 1 |
| 6 |
| 3 |
| 4 |
| 2 |
| 3 |
=2+9-8
=3;
(2)23-
| 8 |
| 9 |
| 3 |
| 4 |
| 1 |
| 27 |
=23-
| 2 |
| 3 |
=23-18
=5;
(3)
| 8 |
| 13 |
| 1 |
| 7 |
| 6 |
| 13 |
=
| 8 |
| 13 |
| 1 |
| 7 |
| 1 |
| 7 |
| 6 |
| 13 |
=(
| 6 |
| 13 |
| 8 |
| 13 |
| 1 |
| 7 |
=
| 14 |
| 13 |
| 1 |
| 7 |
=
| 2 |
| 13 |
(4)5÷[(
| 2 |
| 3 |
| 1 |
| 5 |
| 1 |
| 13 |
=5÷(
| 13 |
| 15 |
| 1 |
| 13 |
=5÷
| 1 |
| 15 |
=5×15
=75;
(5)
| 4 |
| 25 |
| 4 |
| 25 |
=
| 4 |
| 25 |
=
| 4 |
| 25 |
=
| 72 |
| 5 |
(6)(
| 1 |
| 2 |
| 1 |
| 6 |
| 3 |
| 5 |
| 1 |
| 5 |
=(
| 3 |
| 6 |
| 1 |
| 6 |
| 3 |
| 5 |
| 1 |
| 5 |
=
| 1 |
| 3 |
| 3 |
| 5 |
=1.
点评:混合运算的关键是抓住运算顺序,正确按运算顺序计算,适当利用运算定律简算.
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