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解方程:8.8+4x=4012x÷3=166x+2x=563x-0.5x=50.24x-1.8=4.21-5x=0.4.

题目详情
解方程:
8.8+4x=40                  12x÷3=16                  6x+2x=56
3x-0.5x=5                0.24x-1.8=4.2               1-5x=0.4.
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答案和解析
(1)8.8+4x=40
    8.8+4x-8.8=40-8.8
            4x=31.2
         4x÷4=31.2÷4
             x=7.8;

(2)12x÷3=16                 
12x÷3×3=16×3
      12x=48
  12x÷12=48÷12
        x=4;

(3)6x+2x=56
        8x=56               
     8x÷8=56÷8
         x=7;

(4)3x-0.5x=5
        2.5x=5
   2.5x÷2.5=5÷2.5
           x=2;

(5)0.24x-1.8=4.2
 0.24x-1.8+1.8=4.2+1.8
         0.24x=6
   0.24x÷0.24=6÷0.24
             x=25;

(6)1-5x=0.4
  1-5x+5x=0.4+5x
    0.4+5x=1
0.4+5x-0.4=1-0.4
        5x=0.6
      5x÷5=0.6÷5
          x=0.12.