解方程，带“★”号的要写出检验过程．30x-3.2×1.5=4.2★9-0.8x=1.9246÷x-4.6=0.45（2x-1）=305x-6.1+3x=7.910.5+0.7x=x

Question

解方程，带“★”号的要写出检验过程．

30x-3.2×1.5=4.2	★9-0.8x=1.92	46÷x-4.6=0.4
5（2x-1）=30	5x-6.1+3x=7.9	10.5+0.7x=x

Answer 1

①30x-3.2×1.5=4.2
          30x-4.8+4.8=4.2+4.8
                       30x=9
                  30x÷30=9÷30
                           x=0.3

         ②9-0.8x=1.92
     9-0.8x+0.8x=1.92+0.8x
1.92+0.8x-1.92=9-1.92
                 0.8x=0.08
           0.8x÷0.8=7.08÷0.8
                      x=8.85
检验：把x=8.85代入原方程，
左边=9-0.8×8.85
=9-7.08
=1.92
右边=1.92
左边=右边，
所以x=8.85是原方程的解．

  ③46÷x-4.6=0.4  
46÷x-4.6+4.6=0.4+4.6
          46÷x×x=5x
                  5x=46
               5x÷5=46÷5
                     x=9.2
  
④5（2x-1）=30
           10x-5=30
        10x-5+5=30+5
          10x÷10=35÷10
                   x=3.5

⑤5x-6.1+3x=7.9 
   8x-6.1+6.1=7.9+6.1
                 8x=14
              8x÷8=14÷8
                     x=1.75

   ⑥10.5+0.7x=x
10.5+0.7x-0.7x=x-0.7
                0.3x=10.5
          0.3x÷0.3=10.5÷0.3
                      x=(1)/(35)