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我能很快算出下面的题目相信你也能行.

来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/07/18 03:32:57
①9
2
5 -(3
3
7 +0.4),
=9
2
5 -3
3
7 -
2
5 ,
=(9
2
5 -
2
5 )-3
3
7 ,
=9-3
3
7 ,
=5
4
7 ;

②7.8×
1
5 +2.2×20%,
=7.8×0.2+2.2×0.2,
=(7.8+2.2)×0.2,
=10×0.2,
=2;

③34.7-
7
15 +65.3-
8
15 ,
=(34.7+65.3)-(
7
15 +
8
15 ),
=100-1,
=99;

④(
3
4 +
11
6 -
13
24 )×12,
=
3
4 ×12+
11
6 ×12-
13
24 ×12,
=9+22-6.5,
=24.5;

⑤0.25×32×12.5,
=0.25×4×8×12.5,
=(0.25×4)×(8×12.5),
=1×100,
=100;


7
12 ×[
3
4 -(
11
20 -
1
2 )],
=
7
12 ×[
3
4 -(
11
20 -
10
20 )],
=
7
12 ×[
3
4 -
1
20 ],
=
7
12 ×[
15
20 -
1
20 ],
=
7
12 ×
7
10 ,
=
49
120 ;


1
3 x+
5
9 x=1.4,

1
3 +
5
9 )x=1.4,
8
9 x=1.4,
8
9 x×
9
8 =1.4×
9
8 ,
x=
63
40 ;

⑧16:x=0.75:
15
8 ,
0.75x=16×
15
8 ,
0.75x=30,
0.75x÷0.75=30÷0.75,
x=40.