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求未知数x160×25%-1.3x=17.9x5-x6=0.40.30.5=x+12x−1.

题目详情
求未知数x
160×25%-1.3x=17.9
x
5
-
x
6
=0.4
0.3
0.5
=
x+1
2x−1
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答案和解析
(1)160×25%-1.3x=17.9
              40-1.3x=17.9
         40-1.3x+1.3x=17.9+1.3x
            17.9+1.3x=40
       17.9+1.3x-17.9=40-17.9
                 1.3x=22.1
            1.3x÷1.3=22.1÷1.3 
                    x=17

(2)
x
5
-
x
6
=0.4
x
5
-
x
6
)×30=0.4×30
       6x-5x=12
           x=12 

(3)
0.3
0.5
=
x+1
2x−1

0.3×(2x-1)=0.5×(x+1)
    0.6x-0.3=0.5x+0.5
 0.6x-0.3+0.3=0.5x+0.5+0.3
        0.1x=0.8
   0.1x÷0.1=0.8÷0.1
           x=8