Estou com duvida na 20
Anexos:
Anônimo:
qual a 20? cortou....
Respostas
respondido por:
1
a)
3 15
----- = ------
4 x
3.x = 4.15
3x = 60
x = 60/3
x = 20
R.: 15
------
20
¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
b)
8 2
------ = ------
48 x
8x = 48.2
8x = 96
x = 96/8
x = 12
Resp.: 2
------
12
¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
c)
2 = x
------- -------
3 27
2.27
------- = x
3
2.9 = x
18 = x
x = 18
18
R.: = -------
27
d)
6 x
-------- = ---------
20 50
6.50 300
x = -------- = ------ = 15
20 20
15
R.: = -----
50
**************************************
5 x
------ = ------
7 y
5y = 7x
5y - 7x = 0
x + y = 60
5y - 7x = 0
y + x = 60 (-5)
5y - 7x = 0
- 5y - 5x = - 300
-----------------------------
- 12x = - 300 (-1)
12x = 300
x = 300/12
x = 25
x + y = 60
25 + y = 60
y = 60 - 25
y = 35
Resp.: x = 25
------ ------
y 35
*********************************
a)
2 x
----- = ------
3 30
2.30 x 60
------- = => ----- = x ; x = 20
3 3
R.: 20
--------
30
b)
36 = x
------ --------
40 20
36.20 (:20) = x 36.1
--------- => --------- = x ; x = 36/2 ; x = 18
40 (:20) 2
R.: 18
---------
20
¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
c)
20 16
------ = ------
25 x
20x = 25.16
20x = 400
x = 400/20
x = 20
Resp.: 16
------
20
_____________________________
d)
7 35
------ = -------
9 x
7.x = 9.35
x = 9.35 ; x = 9.5 ; x = 45
-------
7
R.: 35
------
45
**************************
e)
x 9 (:9)
------ = ----------
5 45 (:9)
x 1
----- = ----
5 5
5x = 5
x = 5/5
x = 1
R.: 1
------
5
**************************
f) está cortada a fração final
3 7
------ = --------
x ?
****************************
Última:
6 x
----- = ------
11 y
6y = 11x
6y - 11x = 0
x - y = 45
x - y = 45 (6)
- 11x + 6y = 0
6x - 6y = 270
- 11x + 6y = 0 (+)
---------------------------
- 5x = 270
5x = - 270
x = - 54
x - y = 45
- 54 - y = 45
- 54 - 45 = y
- 99 = y
y = - 99
x = - 54 54
----- ------ = ------
y - 99 99
3 15
----- = ------
4 x
3.x = 4.15
3x = 60
x = 60/3
x = 20
R.: 15
------
20
¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
b)
8 2
------ = ------
48 x
8x = 48.2
8x = 96
x = 96/8
x = 12
Resp.: 2
------
12
¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
c)
2 = x
------- -------
3 27
2.27
------- = x
3
2.9 = x
18 = x
x = 18
18
R.: = -------
27
d)
6 x
-------- = ---------
20 50
6.50 300
x = -------- = ------ = 15
20 20
15
R.: = -----
50
**************************************
5 x
------ = ------
7 y
5y = 7x
5y - 7x = 0
x + y = 60
5y - 7x = 0
y + x = 60 (-5)
5y - 7x = 0
- 5y - 5x = - 300
-----------------------------
- 12x = - 300 (-1)
12x = 300
x = 300/12
x = 25
x + y = 60
25 + y = 60
y = 60 - 25
y = 35
Resp.: x = 25
------ ------
y 35
*********************************
a)
2 x
----- = ------
3 30
2.30 x 60
------- = => ----- = x ; x = 20
3 3
R.: 20
--------
30
b)
36 = x
------ --------
40 20
36.20 (:20) = x 36.1
--------- => --------- = x ; x = 36/2 ; x = 18
40 (:20) 2
R.: 18
---------
20
¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
c)
20 16
------ = ------
25 x
20x = 25.16
20x = 400
x = 400/20
x = 20
Resp.: 16
------
20
_____________________________
d)
7 35
------ = -------
9 x
7.x = 9.35
x = 9.35 ; x = 9.5 ; x = 45
-------
7
R.: 35
------
45
**************************
e)
x 9 (:9)
------ = ----------
5 45 (:9)
x 1
----- = ----
5 5
5x = 5
x = 5/5
x = 1
R.: 1
------
5
**************************
f) está cortada a fração final
3 7
------ = --------
x ?
****************************
Última:
6 x
----- = ------
11 y
6y = 11x
6y - 11x = 0
x - y = 45
x - y = 45 (6)
- 11x + 6y = 0
6x - 6y = 270
- 11x + 6y = 0 (+)
---------------------------
- 5x = 270
5x = - 270
x = - 54
x - y = 45
- 54 - y = 45
- 54 - 45 = y
- 99 = y
y = - 99
x = - 54 54
----- ------ = ------
y - 99 99
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