问题 解答题
求未知数x.
(1)4-16x=1
(2)
2
5
2
15
=x:(16-5)
(3)
3
5
x-
3
10
x=1
5
7
           
(4)
3x-1
2x+1
=
5
6
答案

(1)4-16x=1

     4-16x+16x=1+16x,

         1+16x=4,

       1+16x-1=4-1,

           16x=3,

       16x÷16=3÷16,

             x=

3
16

(2)

2
5
2
15
=x:(16-5),

       

2
15
x=
2
5
×11,

  

2
15
15
2
=
2
5
×11×
15
2

           x=33;

(3)

3
5
x-
3
10
x=1
5
7

          

3
10
x=
12
7

     

3
10
10
3
=
12
7
×
10
3

              x=

40
7

           

(4)

3x-1
2x+1
=
5
6

6×(3x-1)=5×(2x+1),

      18x-6=10x+5,

    18x-6+6=10x+5+6,

        18x=10x+11,

    18x-10x=10x+11-10x,

         8x=11,

      8x÷8=11÷8,

          x=

11
8

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