题目内容
(2012?遂昌县)用递等式计算.
①[1-(
+
)]×36
②(
+
)×36
③7.5×4.7+4.7×2.5
④25.3×12-33.46÷0.35
⑤
×[
÷(1-
)]
⑥
+(
-
)÷
.
①[1-(
1 |
8 |
2 |
3 |
②(
2 |
9 |
7 |
12 |
③7.5×4.7+4.7×2.5
④25.3×12-33.46÷0.35
⑤
5 |
6 |
2 |
3 |
13 |
15 |
⑥
1 |
4 |
5 |
8 |
3 |
10 |
1 |
2 |
分析:①④⑤⑥根据四则混合运算的运算顺序计算即可.
②③可据乘法分配律进行计算;
②③可据乘法分配律进行计算;
解答:解:①[1-(
+
)]×36,
=[1-(
+
)]×36,
=[1-
]×36,
=
×36,
=
;
②(
+
)×36,
=36×
+
×36,
=8+21,
=29;
③7.5×4.7+4.7×2.5,
=4.7×(7.5+2.5),
=4.7×10,
=47;
④25.3×12-33.46÷0.35,
=303.6-95.6,
=208;
⑤
×[
÷(1-
)],
=
×[
÷
],
=
×[
×
],
=
×5,
=4
;
⑥
+(
-
)÷
,
=
+(
-
)×2,
=
+
×2,
=
+
,
=
.
1 |
8 |
2 |
3 |
=[1-(
3 |
24 |
16 |
24 |
=[1-
19 |
24 |
=
5 |
24 |
=
15 |
2 |
②(
2 |
9 |
7 |
12 |
=36×
2 |
9 |
7 |
12 |
=8+21,
=29;
③7.5×4.7+4.7×2.5,
=4.7×(7.5+2.5),
=4.7×10,
=47;
④25.3×12-33.46÷0.35,
=303.6-95.6,
=208;
⑤
5 |
6 |
2 |
3 |
13 |
15 |
=
5 |
6 |
2 |
3 |
2 |
15 |
=
5 |
6 |
2 |
3 |
15 |
2 |
=
5 |
6 |
=4
1 |
6 |
⑥
1 |
4 |
5 |
8 |
3 |
10 |
1 |
2 |
=
1 |
4 |
25 |
40 |
12 |
40 |
=
1 |
4 |
13 |
40 |
=
5 |
20 |
13 |
20 |
=
9 |
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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