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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
[212-00]
(1)
2
x
＋
7
x
＋
12
=
0
(2)
2
x
＋
6
x
＋
5
=
0
(3)
2
x
＋
5
x
−
24
=
0
(4)
2
x
＋
13
x
＋
40
=
0
(5)
2
x
−
6
x
＋
8
=
0
(6)
2
x
−
x
−
20
=
0
(7)
2
x
＋
7
x
＋
10
=
0
(8)
2
x
＋
x
−
30
=
0
(9)
2
x
＋
4
x
−
21
=
0
(10)
2
x
＋
5
x
＋
4
=
0
©2025 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
2
x
＋
7
x
＋
12
=
0
2
49
49
x
＋
7
x
＋
−
＋
12
4
4
=
0
7
2
(
x
＋
)
2
1
=
4
7
x
＋
2
1
=
±
2
x
=
−3
，
−4
(2)
2
x
＋
6
x
＋
5
=
0
2
x
＋
6
x
＋
9
−
9
＋
5
=
0
2
(
x
＋
3
)
=
4
x
＋
3
=
±
2
x
=
−1
，
−5
(3)
2
x
＋
5
x
−
24
=
0
2
25
25
x
＋
5
x
＋
−
−
24
4
4
=
0
5
2
(
x
＋
)
2
121
=
4
5
x
＋
2
11
=
±
2
x
=
−8
，
3
(4)
2
x
＋
13
x
＋
40
=
0
2
169
169
x
＋
13
x
＋
−
＋
40
4
4
=
0
13
2
(
x
＋
)
2
9
=
4
13
x
＋
2
3
=
±
2
x
=
−8
，
−5
(5)
2
x
−
6
x
＋
8
=
0
2
x
−
6
x
＋
9
−
9
＋
8
=
0
2
(
x
−
3
)
=
1
x
−
3
=
±
1
x
=
4
，
2
(6)
2
x
−
x
−
20
=
0
2
1
1
x
−
x
＋
−
−
20
4
4
=
0
1
2
(
x
−
)
2
81
=
4
1
x
−
2
9
=
±
2
x
=
−4
，
5
(7)
2
x
＋
7
x
＋
10
=
0
2
49
49
x
＋
7
x
＋
−
＋
10
4
4
=
0
7
2
(
x
＋
)
2
9
=
4
7
x
＋
2
3
=
±
2
x
=
−5
，
−2
(8)
2
x
＋
x
−
30
=
0
2
1
1
x
＋
x
＋
−
−
30
4
4
=
0
1
2
(
x
＋
)
2
121
=
4
1
x
＋
2
11
=
±
2
x
=
−6
，
5
(9)
2
x
＋
4
x
−
21
=
0
2
x
＋
4
x
＋
4
−
4
−
21
=
0
2
(
x
＋
2
)
=
25
x
＋
2
=
±
5
x
=
3
，
−7
(10)
2
x
＋
5
x
＋
4
=
0
2
25
25
x
＋
5
x
＋
−
＋
4
4
4
=
0
5
2
(
x
＋
)
2
9
=
4
5
x
＋
2
3
=
±
2
x
=
−1
，
−4