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©2025 数学クラブ http://sugaku.club/
月 日( )
● 次の方程式を解きなさい
[225-00]
(1)
2
x
−
7
x
+
8
=
−13
x
+
15
(2)
2
x
+
8
x
+
7
=
2
(
−3
x
−
19
)
(3)
(
x
+
8
)
(
x
+
2
)
=
7
x
+
20
(4)
(
x
+
4
)
(
x
−
3
)
=
x
+
13
(5)
(
x
+
8
)
(
x
+
8
)
=
3
(
2
x
+
13
)
©2025 数学クラブ http://sugaku.club/
月 日( )
【解答例】
(1)
2
x
−
7
x
+
8
=
−13
x
+
15
2
x
+
6
x
−
7
=
0
(
x
−
1
)
(
x
+
7
)
=
0
x
=
1
,
−7
(2)
2
x
+
8
x
+
7
=
2
(
−3
x
−
19
)
2
x
+
14
x
+
45
=
0
(
x
+
9
)
(
x
+
5
)
=
0
x
=
−9
,
−5
(3)
(
x
+
8
)
(
x
+
2
)
=
7
x
+
20
2
x
+
10
x
+
16
=
7
x
+
20
2
x
+
3
x
−
4
=
0
(
x
+
4
)
(
x
−
1
)
=
0
x
=
−4
,
1
(4)
(
x
+
4
)
(
x
−
3
)
=
x
+
13
2
x
+
x
−
12
=
x
+
13
2
x
−
25
=
0
(
x
+
5
)
(
x
−
5
)
=
0
x
=
−5
,
5
(5)
(
x
+
8
)
(
x
+
8
)
=
3
(
2
x
+
13
)
2
x
+
16
x
+
64
=
6
x
+
39
2
x
+
10
x
+
25
=
0
2
(
x
+
5
)
=
0
x
=
−5