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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
＋
3
x
−
28
=
0
(2)
2
x
−
8
x
＋
16
=
0
(3)
2
x
＋
2
x
−
35
=
0
(4)
2
x
＋
9
x
＋
20
=
0
(5)
2
x
＋
8
x
＋
15
=
0
(6)
2
x
−
7
x
＋
10
=
0
(7)
2
x
＋
3
x
−
10
=
0
(8)
2
x
＋
4
x
−
12
=
0
(9)
2
x
−
13
x
＋
40
=
0
(10)
2
x
＋
10
x
＋
21
=
0
©2026 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
2
x
＋
3
x
−
28
=
0
2
9
9
x
＋
3
x
＋
−
−
28
4
4
=
0
3
2
(
x
＋
)
2
121
=
4
3
x
＋
2
11
=
±
2
x
=
−7
，
4
(2)
2
x
−
8
x
＋
16
=
0
2
(
x
−
4
)
=
0
x
=
4
(3)
2
x
＋
2
x
−
35
=
0
2
x
＋
2
x
＋
1
−
1
−
35
=
0
2
(
x
＋
1
)
=
36
x
＋
1
=
±
6
x
=
5
，
−7
(4)
2
x
＋
9
x
＋
20
=
0
2
81
81
x
＋
9
x
＋
−
＋
20
4
4
=
0
9
2
(
x
＋
)
2
1
=
4
9
x
＋
2
1
=
±
2
x
=
−5
，
−4
(5)
2
x
＋
8
x
＋
15
=
0
2
x
＋
8
x
＋
16
−
16
＋
15
=
0
2
(
x
＋
4
)
=
1
x
＋
4
=
±
1
x
=
−5
，
−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
=
2
，
5
(7)
2
x
＋
3
x
−
10
=
0
2
9
9
x
＋
3
x
＋
−
−
10
4
4
=
0
3
2
(
x
＋
)
2
49
=
4
3
x
＋
2
7
=
±
2
x
=
2
，
−5
(8)
2
x
＋
4
x
−
12
=
0
2
x
＋
4
x
＋
4
−
4
−
12
=
0
2
(
x
＋
2
)
=
16
x
＋
2
=
±
4
x
=
2
，
−6
(9)
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
(10)
2
x
＋
10
x
＋
21
=
0
2
x
＋
10
x
＋
25
−
25
＋
21
=
0
2
(
x
＋
5
)
=
4
x
＋
5
=
±
2
x
=
−7
，
−3