解方程.(1)4÷23(x?1)=25(2)23x+12x=42(3)6x+4.5=9x-1.2(4)(47x):23=4:7.

解方程.(1)4÷23(x?1)=25(2)23x+12x=42(3)6x+4.5=9x-1.2(4)(47x):23=4:7.

(1)
2
3
(x?1)=
2
5

    4÷[4÷
2
3
(x?1)]=4÷
2
5

       
2
3
(x?1)×
3
2
=10×
3
2

                x-1+1=15+1,
                    x=16;

(2)
2
3
x+
1
2
x=42

         
7
6
x=42

     
7
6
6
7
=42×
6
7

             x=36;

(3)6x+4.5=9x-1.2,
  6x+4.5-6x=9x-1.2-6x,
    4.5+1.2=3x-1.2+1.2,
     5.7÷3=3x÷3,
          x=1.9;

(4)(
4
7
x):
2
3
=4:7

        
4
7
x×7
=
2
3
×
4,
          4x÷4=
8
3
÷4

              x=
2
3
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