题目内容

脱式计算,能简算的要简算.
6
25
÷9+
6
25
×
8
9
1
2
-
3
7
)×
7
25
+
18
25
1
2
-
1
3
+
1
4
)×48
17×(
2
17
+
1
15
)×15
1
5×6
+
1
6×7
+
1
7×8
+
1
8×9
+
1
9×10
分析:(1)先把除法变成乘法,再运用乘法分配律简算;
(2)先运用乘法分配律简算,再运用加法结合律简算;
(3)运用乘法分配律简算;
(4)先把17×15结合在一起,再运用乘法分配律简算;
(5)
1
5×6
=
1
5
-
1
6
1
6×7
=
1
6
-
1
7
…由此化简求解.
解答:解:(1)
6
25
÷9+
6
25
×
8
9

=
6
25
×
1
9
+
6
25
×
8
9

=
6
25
×(
1
9
+
8
9
),
=
6
25
×1,
=
6
25


(2)(
1
2
-
3
7
)×
7
25
+
18
25

=
1
2
×
7
25
-
3
7
×
7
25
+
18
25

=
7
50
-
3
25
+
18
25

=
7
50
+(
18
25
-
13
25
),
=
7
50
+
1
5

=
17
50


(3)(
1
2
-
1
3
+
1
4
)×48,
=48×
1
2
-
1
3
×48+
1
4
×48,
=24-16+12,
=8+12,
=20;

(4)17×(
2
17
+
1
15
)×15,
=(17×15)×(
2
17
+
1
15
),
=(17×
2
17
)×15+(15×
1
15
)×17,
=2×15+1×17,
=30+17,
=47;

(5)
1
5×6
+
1
6×7
+
1
7×8
+
1
8×9
+
1
9×10

=
1
5
-
1
6
+
1
6
-
1
7
+
1
7
-
1
8
+
1
8
-
1
9
+
1
9
-
1
10

=
1
5
-
1
10

=
1
10
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.
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