题目内容
脱式计算?(能简算的要用简便方法计算)
1÷(
+
)×
86×
+13÷
+
-[
÷(
+
)]
+
÷(
-
)
1÷(
3 |
4 |
1 |
3 |
13 |
24 |
4 |
5 |
5 |
4 |
4 |
3 |
15 |
22 |
3 |
8 |
7 |
16 |
3 |
4 |
5 |
6 |
1 |
6 |
1 |
3 |
1 |
4 |
考点:分数的四则混合运算,运算定律与简便运算
专题:运算顺序及法则,运算定律及简算
分析:(1)先算加法,再算除法,最后算乘法;
(2)把除法改为乘法,进一步利用乘法分配律简算;
(3)先算加法,再算除法,最后算减法;
(4)先算减法,再算除法,最后算加法.
(2)把除法改为乘法,进一步利用乘法分配律简算;
(3)先算加法,再算除法,最后算减法;
(4)先算减法,再算除法,最后算加法.
解答:
解:(1)1÷(
+
)×
=1÷
×
=1×
×
=
;
(2)86×
+13÷
+
=86×
+13×
+
=(86+13+1)×
+
=100×
+
=80+
=80
;
(3)
-[
÷(
+
)]
=
-[
÷
]
=
-[
×
]
=
-
=
;
(4)
+
÷(
-
)
=
+
÷
=
+
×12
=
+2
=2
.
3 |
4 |
1 |
3 |
13 |
24 |
=1÷
13 |
12 |
13 |
24 |
=1×
12 |
13 |
13 |
24 |
=
1 |
2 |
(2)86×
4 |
5 |
5 |
4 |
4 |
3 |
=86×
4 |
5 |
4 |
5 |
4 |
3 |
=(86+13+1)×
4 |
5 |
8 |
15 |
=100×
4 |
5 |
8 |
15 |
=80+
8 |
15 |
=80
8 |
15 |
(3)
15 |
22 |
3 |
8 |
7 |
16 |
3 |
4 |
=
15 |
22 |
3 |
8 |
19 |
16 |
=
15 |
22 |
3 |
8 |
16 |
19 |
=
15 |
22 |
6 |
19 |
=
153 |
418 |
(4)
5 |
6 |
1 |
6 |
1 |
3 |
1 |
4 |
=
5 |
6 |
1 |
6 |
1 |
12 |
=
5 |
6 |
1 |
6 |
=
5 |
6 |
=2
5 |
6 |
点评:分数四则混合运算的关键是抓住运算顺序,正确按运算书序计算,适当利用运算定律简算.
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