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正确、合理、灵活的计算,求未知数1.25×4×0.6×0.8×2.5516×[225+(23-25)÷13]415+4.2×757+127×415312×115÷(4.5-0.625÷516)÷30%115:127=X:9145×0.36-0.75X=35.

题目详情
正确、合理、灵活的计算,求未知数
1.25×4×0.6×0.8×2.5 
5
16
×[2
2
5
+(
2
3
-
2
5
)÷
1
3
]
4
1
5
+4.2×7
5
7
+1
2
7
×4
1
5
3
1
2
×1
1
5
÷(4.5-0.625÷
5
16
)÷30%
1
1
5
:1
2
7
=X:
9
14
5×0.36-0.75X=
3
5
▼优质解答
答案和解析
(1)1.25×4×0.6×0.8×2.5,
=(1.25×0.8)×(2.5×4)×0.6,
=1×10×0.6,
=6;

(2)
5
16
×[2
2
5
+(
2
3
-
2
5
)÷
1
3
],
=
5
16
×[2
2
5
+(
2
3
2
5
)÷
1
3
],
=
5
16
×[2
2
5
+(
10
15
6
15
)×3],
=
5
16
×[2
2
5
+
4
15
×3],
=
5
16
×[2
2
5
+
4
5
],
=
5
16
×
16
5

=1;

(3)4
1
5
+4.2×7
5
7
+1
2
7
×4
1
5

=4.2+4.2×7
5
7
+1
2
7
×4.2,
=4.2×(1+7
5
7
+1
2
7
),
=4.2×10,
=42;

(4)3
1
2
×1
1
5
÷(4.5-0.625÷
5
16
)÷30%,
=
7
2
×
6
5
÷(4.5-
5
8
×
16
5
)×
10
3

=
21
5
÷(4.5-2)×
10
3

=
21
5
×
2
5
×
10
3

=(
21
5
×
10
3
)×
2
5

=14×
2
5

=
28
5

=5
3
5


(5)1
1
5
:1
2
7
=X:
9
14

        1
2
7
x=1
1
5
×
9
14

        1
2
7
x=
6
5
×
9
14

      
9
7
7
9
=
6
5
×
9
14
×
7
9

           x=
6
5
×(
9
14
×
7
9
),
           x=
6
5
×
1
2

           x=
3
5


(6)5×0.36-0.75X=
3
5

         1.8-0.75x=0.6,
             0.75x=1.2,
           
3
4
4
3
=1.2×
4
3

                 x=1.6;