问题 解答题
求未知数X:
1-
3
4
X=
3
5
X-
1
4
X=
3
8
4х+3×0.7=14.1.
答案

(1)1-

3
4
X=
3
5

1-

3
4
X+
3
4
X=
3
5
+
3
4
X,

3
5
+
3
4
X=1,

3
5
+
3
4
X-
3
5
=1-
3
5

3
4
X=
2
5

3
4
4
3
=
2
5
×
4
3

X=

8
15

(2)X-

1
4
X=
3
8

(1-

1
4
)X=
3
8

3
4
X=
3
8

3
4
4
3
=
3
8
×
4
3

X=

1
2

(3)4х+3×0.7=14.1,

4х+2.1=14.1,

4х+2.1-2.1=14.1-2.1,

4x=12,

x÷4=12÷4,

x=3.

单项选择题
单项选择题