问题 解答题
X-
1
2
x=12
X+
2
3
x=
5
21
X-
3
5
x=
4
15
X+
4
7
x=
33
49
答案

(1)x-

1
2
x=12,

(1-

1
2
)x=12,

1
2
1
2
=12÷
1
2

x=24;

(2)x+

2
3
x=
5
21

(1+

2
3
)x=
5
21

5
3
x=
5
21

5
3
x÷
5
3
=
5
21
÷
5
3

x=

1
7

(3)x-

3
5
x=
4
15

(1-

3
5
)x=
4
15

2
5
2
5
=
4
15
÷
2
5

x=

2
3

(4)x+

4
7
x=
33
49

(1+

4
7
)x=
33
49

11
7
11
7
=
33
49
÷
11
7

x=

3
7

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