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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
[220-00]
(1)
3
x
(
x
+
8
)
=
0
(2)
5
x
(
x
+
3
)
=
0
(3)
−10
x
(
x
−
8
)
=
0
(4)
10
x
(
x
+
7
)
=
0
(5)
3
x
(
x
+
7
)
=
0
(6)
−5
x
(
x
−
5
)
=
0
(7)
−4
x
(
x
−
1
)
=
0
(8)
−10
x
(
x
−
8
)
=
0
(9)
8
x
(
x
−
5
)
=
0
(10)
−10
x
(
x
+
3
)
=
0
(11)
3
x
(
x
+
1
)
=
0
(12)
6
x
(
x
+
6
)
=
0
©2026 数学クラブ http://sugaku.club/
月 日( )
【解答例】
(1)
3
x
(
x
+
8
)
=
0
x
=
0
,
−8
(2)
5
x
(
x
+
3
)
=
0
x
=
0
,
−3
(3)
−10
x
(
x
−
8
)
=
0
x
=
0
,
8
(4)
10
x
(
x
+
7
)
=
0
x
=
0
,
−7
(5)
3
x
(
x
+
7
)
=
0
x
=
0
,
−7
(6)
−5
x
(
x
−
5
)
=
0
x
=
0
,
5
(7)
−4
x
(
x
−
1
)
=
0
x
=
0
,
1
(8)
−10
x
(
x
−
8
)
=
0
x
=
0
,
8
(9)
8
x
(
x
−
5
)
=
0
x
=
0
,
5
(10)
−10
x
(
x
+
3
)
=
0
x
=
0
,
−3
(11)
3
x
(
x
+
1
)
=
0
x
=
0
,
−1
(12)
6
x
(
x
+
6
)
=
0
x
=
0
,
−6