题目内容
解方程.
9-0.4x=3.8 | 2-
|
|
分析:(1)根据等式的性质,两边同加上0.4x,得3.8+0.4x=9,两边同减去3.8,再同除以0.4即可;
(2)根据等式的性质,两边同加上
x,得
+
x=2,两边同减去
,再同乘
即可;
(3)原式变为(
+
)x=
,即
x=
,根据等式的性质,两边同乘
即可.
(2)根据等式的性质,两边同加上
3 |
4 |
3 |
5 |
3 |
4 |
3 |
5 |
4 |
3 |
(3)原式变为(
3 |
4 |
1 |
2 |
15 |
16 |
5 |
4 |
15 |
16 |
4 |
5 |
解答:解:(1)9-0.4x=3.8,
9-0.4x+0.4x=3.8+0.4x,
3.8+0.4x=9,
3.8+0.4x-3.8=9-3.8,
0.4x=5.2,
0.4x÷0.4=5.2÷0.4,
x=13;
(2)2-
x=
,
2-
x+
x=
+
x,
+
x=2,
+
x-
=2-
,
x=
,
x×
=
×
,
x=
;
(3)
x+
x=
,
(
+
)x=
,
x=
,
x×
=
×
,
x=
.
9-0.4x+0.4x=3.8+0.4x,
3.8+0.4x=9,
3.8+0.4x-3.8=9-3.8,
0.4x=5.2,
0.4x÷0.4=5.2÷0.4,
x=13;
(2)2-
3 |
4 |
3 |
5 |
2-
3 |
4 |
3 |
4 |
3 |
5 |
3 |
4 |
3 |
5 |
3 |
4 |
3 |
5 |
3 |
4 |
3 |
5 |
3 |
5 |
3 |
4 |
7 |
5 |
3 |
4 |
4 |
3 |
7 |
5 |
4 |
3 |
x=
28 |
15 |
(3)
3 |
4 |
1 |
2 |
15 |
16 |
(
3 |
4 |
1 |
2 |
15 |
16 |
5 |
4 |
15 |
16 |
5 |
4 |
4 |
5 |
15 |
16 |
4 |
5 |
x=
3 |
4 |
点评:此题考查了运用等式的性质解方程,即等式两边同加上或同减去、同乘上或同除以一个数(0除外),两边仍相等,同时注意“=”上下要对齐.
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