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©2026 数学クラブ http://sugaku.club/
月 日( )
● 次の方程式を解きなさい
[225-00]
(1)
(
x
+
7
)
(
x
+
9
)
=
4
x
+
27
(2)
2
x
+
2
x
+
6
=
3
(
x
+
26
)
(3)
2
x
−
9
x
+
7
=
−16
x
+
1
(4)
2
x
+
7
x
+
4
=
8
(
x
+
2
)
(5)
2
x
−
10
x
−
1
=
−19
x
+
9
©2026 数学クラブ http://sugaku.club/
月 日( )
【解答例】
(1)
(
x
+
7
)
(
x
+
9
)
=
4
x
+
27
2
x
+
16
x
+
63
=
4
x
+
27
2
x
+
12
x
+
36
=
0
2
(
x
+
6
)
=
0
x
=
−6
(2)
2
x
+
2
x
+
6
=
3
(
x
+
26
)
2
x
−
x
−
72
=
0
(
x
−
9
)
(
x
+
8
)
=
0
x
=
9
,
−8
(3)
2
x
−
9
x
+
7
=
−16
x
+
1
2
x
+
7
x
+
6
=
0
(
x
+
1
)
(
x
+
6
)
=
0
x
=
−1
,
−6
(4)
2
x
+
7
x
+
4
=
8
(
x
+
2
)
2
x
−
x
−
12
=
0
(
x
−
4
)
(
x
+
3
)
=
0
x
=
4
,
−3
(5)
2
x
−
10
x
−
1
=
−19
x
+
9
2
x
+
9
x
−
10
=
0
(
x
+
10
)
(
x
−
1
)
=
0
x
=
−10
,
1