Question

Aplicando as regras da proporção resolva os seguintes casos
(A)12/16=18/×
(B)×/9=2/7
(C)5×-3/14=1/2
(D)×-3/4=×/5
(E)×+3/×-2=3/2
(F)20/×+1=16/×
(G)2×/3=8/6
(H)3/2=×+3/×-1
( I )2×+1/2=9×/2
(J)×/30=4/6

Answer 1

Aplicando as regras da proporção resolva os seguintes casos 

PROPORÇÃO  (só cruzar)
(A)12/16=18/× 

12     18
----- = ----
 16     x

12(x) = 16(18)
12x = 288
x = 288/12
x = 24


(B)×/9=2/7

x         2
----- = ----
9         7

7(x) = 2(9)
7x = 18
x = 18/7

(C)5×-3/14=1/2

5x - 3       1
-------- = -----
   14         2
 
2(5x - 3) = 1(14)
10x - 6 = 14
10x = 14 + 6
10x = 20
x = 20/10
x = 2
 
(D)×-3/4=×/5

x - 3        x
------ = ------
     4        5

4(x) = 5(x - 3)
4x = 5x - 15
4x - 5x = - 15
- 1x = -15
x = - 15/-1
x =+ 15/1
x = 15


(E)×+3/×-2=3/2

x + 3      3
-------- = ---
x - 2       2

3(x - 2)= 2(x + 3)
 3x- 6 = 2x + 6
3x - 6 - 2x = 6
3x - 2x = 6 + 6
1x = 12
x = 12/1
x = 12

(F)20/×+1=16/×


 20         16
------- = ------
x + 1       x

20(x) = 16(x + 1)
20x = 16x + 16
20x - 16x = 16
4x = 16
x = 16/4
x = 4

(G)2×/3=8/6

2x     8
----- = ---
 3        6

6(2x) = 3(8)
12x = 24
x = 24/12
x = 2

(H)3/2=×+3/×-1

3       x +3
--- = --------
2       x - 1

3(x - 1) = 2(x + 3)
3x - 3 = 2x + 6
3x - 3 - 2x = 6
3x - 2x = 6 + 3
1x = 9
x = 9/1
x = 9

( I )2×+1/2=9×/2

2x + 1     9x
-------- = ----
  2            2

2(9x) = 2(2x + 1)
18x = 4x + 2
18x - 4x = 2
14x = 2
x = 2/14   ( divide AMBOS por 2)
x = 1/7
 
(J)×/30=4/6

x     4
---= ----
30   6

6(x) = 4(30)
6x = 120
x = 120/6
x = 20