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(2012•长寿区)求未知数Χ0.5×(Χ-0.4)=5.8310+710Χ=311034:12=Χ:45Χ4=30%

题目详情
(2012•长寿区)求未知数Χ
0.5×(Χ-0.4)=5.8
3
10
+
7
10
Χ=3
1
10

3
4
1
2
=Χ:
4
5

Χ
4
=30%
▼优质解答
答案和解析
(1)0.5×(X-0.4)=5.8,
        0.5×X-0.5×0.4=5.8
               0.5X-0.2=5.8,
           0.5X-0.2+0.2=5.8+0.2,
                   0.5X=6,
              0.5X÷0.5=6÷0.5,
                      X=12;

(2)
3
10
+
7
10
X=3
1
10

 
3
10
+
7
10
X-
3
10
=3
1
10
-
3
10

        
7
10
X=
14
5

   
7
10
10
7
=
14
5
×
10
7

            X=4;

(3)
3
4
1
2
=X:
4
5

       
1
2
X=
3
4
×
4
5

     
1
2
X×2=
3
5
×2,
          X=1.2;

(4)
X
4
=30%,
    
X
4
=
3
10

    10X=12,
10X÷10=12÷10,
      X=1.2.