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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
[212-00]
(1)
2
x
＋
5
x
＋
4
=
0
(2)
2
x
＋
3
x
−
70
=
0
(3)
2
x
＋
11
x
＋
10
=
0
(4)
2
x
−
5
x
−
14
=
0
(5)
2
x
＋
7
x
＋
12
=
0
(6)
2
x
−
7
x
＋
10
=
0
(7)
2
x
−
x
−
30
=
0
(8)
2
x
−
x
−
6
=
0
(9)
2
x
＋
12
x
＋
27
=
0
(10)
2
x
＋
15
x
＋
56
=
0
©2026 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
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
=
−4
，
−1
(2)
2
x
＋
3
x
−
70
=
0
2
9
9
x
＋
3
x
＋
−
−
70
4
4
=
0
3
2
(
x
＋
)
2
289
=
4
3
x
＋
2
17
=
±
2
x
=
−10
，
7
(3)
2
x
＋
11
x
＋
10
=
0
2
121
121
x
＋
11
x
＋
−
＋
10
4
4
=
0
11
2
(
x
＋
)
2
81
=
4
11
x
＋
2
9
=
±
2
x
=
−10
，
−1
(4)
2
x
−
5
x
−
14
=
0
2
25
25
x
−
5
x
＋
−
−
14
4
4
=
0
5
2
(
x
−
)
2
81
=
4
5
x
−
2
9
=
±
2
x
=
−2
，
7
(5)
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
=
−4
，
−3
(6)
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
(7)
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
=
−5
，
6
(8)
2
x
−
x
−
6
=
0
2
1
1
x
−
x
＋
−
−
6
4
4
=
0
1
2
(
x
−
)
2
25
=
4
1
x
−
2
5
=
±
2
x
=
3
，
−2
(9)
2
x
＋
12
x
＋
27
=
0
2
x
＋
12
x
＋
36
−
36
＋
27
=
0
2
(
x
＋
6
)
=
9
x
＋
6
=
±
3
x
=
−9
，
−3
(10)
2
x
＋
15
x
＋
56
=
0
2
225
225
x
＋
15
x
＋
−
＋
56
4
4
=
0
15
2
(
x
＋
)
2
1
=
4
15
x
＋
2
1
=
±
2
x
=
−8
，
−7