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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
＋
19
x
＋
90
=
0
(2)
2
x
＋
8
x
＋
15
=
0
(3)
2
x
−
7
x
＋
12
=
0
(4)
2
x
＋
2
x
−
15
=
0
(5)
2
x
−
14
x
＋
45
=
0
(6)
2
x
＋
12
x
＋
32
=
0
(7)
2
x
−
3
x
−
10
=
0
(8)
2
x
−
8
x
＋
7
=
0
(9)
2
x
＋
8
x
＋
7
=
0
(10)
2
x
＋
3
x
−
18
=
0
©2025 数学クラブ http://sugaku.club/
月 日（ ）
【解答例】
(1)
2
x
＋
19
x
＋
90
=
0
2
361
361
x
＋
19
x
＋
−
＋
90
4
4
=
0
19
2
(
x
＋
)
2
1
=
4
19
x
＋
2
1
=
±
2
x
=
−10
，
−9
(2)
2
x
＋
8
x
＋
15
=
0
2
x
＋
8
x
＋
16
−
16
＋
15
=
0
2
(
x
＋
4
)
=
1
x
＋
4
=
±
1
x
=
−5
，
−3
(3)
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
(4)
2
x
＋
2
x
−
15
=
0
2
x
＋
2
x
＋
1
−
1
−
15
=
0
2
(
x
＋
1
)
=
16
x
＋
1
=
±
4
x
=
−5
，
3
(5)
2
x
−
14
x
＋
45
=
0
2
x
−
14
x
＋
49
−
49
＋
45
=
0
2
(
x
−
7
)
=
4
x
−
7
=
±
2
x
=
5
，
9
(6)
2
x
＋
12
x
＋
32
=
0
2
x
＋
12
x
＋
36
−
36
＋
32
=
0
2
(
x
＋
6
)
=
4
x
＋
6
=
±
2
x
=
−8
，
−4
(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
=
5
，
−2
(8)
2
x
−
8
x
＋
7
=
0
2
x
−
8
x
＋
16
−
16
＋
7
=
0
2
(
x
−
4
)
=
9
x
−
4
=
±
3
x
=
7
，
1
(9)
2
x
＋
8
x
＋
7
=
0
2
x
＋
8
x
＋
16
−
16
＋
7
=
0
2
(
x
＋
4
)
=
9
x
＋
4
=
±
3
x
=
−7
，
−1
(10)
2
x
＋
3
x
−
18
=
0
2
9
9
x
＋
3
x
＋
−
−
18
4
4
=
0
3
2
(
x
＋
)
2
81
=
4
3
x
＋
2
9
=
±
2
x
=
−6
，
3