Question

Responda: A)X+2y=12 B)x-y=7 C)2x-y=1 D)x-2y=4 E)X+3y=5

Answer 1

a)

x = 0
x + 2y = 12
0 + 2y = 12
2y = 12
y = 12/2
y = 6

x = - 2
x + 2y = 12
- 2 + 2y = 12
2y = 12 + 2
2y = 14
y = 14/2
y = 7

x = 2
x + 2y = 12
2 + 2y = 12
2y = 12 - 2
2y = 10
y = 10/2
y = 5

x = 4
x + 2y = 12
4 + 2y = 12
2y = 12 - 4
2y = 8
y = 8/2
y = 4

R.: 
(0;6)
(-2;7)
(2;5)
(4;4)

************************
B)
x = 0
x - y = 7
0 - y = 7
- y = 7 (-1)
y = - 7

y = 1
x - y = 7
x - 1 = 7
x = 7 + 1
x = 8

y = - 2
x - y = 7
x - (-2) = 7
x + 2 = 7
x = 7 - 2
x = 5

y = 0
x - y = 7
x - 0 = 7
x = 7

R.: 
(0;-7)
(8;1)
(5;-2)
(7;0)

¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
C)
(0;-1)
(1/2;0)
(1;1)
(4;7)

*************************
x = 0
2x - y = 1
2.0 - y = 1 
- y = 1 (-1)
y = - 1

y = 0
2x - y = 1
2x - 0 = 1
2x = 1
x = 1/2

y = 1
2x - y = 1
2x - 1 = 1
2x = 1 + 1
2x = 2
x = 2/2
x = 1

y = - 1
2x - y = 1
2x - (-1) = 1
2x + 1 = 1
2x = 1 - 1
2x = 0
x = 0/2
x = 0

y = 7
2x - y = 1
2x - 7 = 1
2x = 1 + 7
2x = 8
x = 8/2
x = 4

******************************
D)
(0; - 2)
(2; - 1)
(6;1)
(-2; -3)

**********************
x = 0
x - 2y = 4
0 - 2y = 4 
- 2y = 4 (-1)
2y = - 4
y = - 4/2
y = - 2

x = 2
x - 2y = 4
2 - 2y = 4
2 - 4 = 2y
 - 2 = 2y
2y = - 2
y = - 2/2
y = - 1


y = 1
x - 2y = 4
x - 2.1 = 4
x - 2 = 4
x = 4 + 2
x = 6

x = - 2
x - 2y = 4
- 2 - 2y = 4
- 2 - 4 = 2y
- 6 = 2y
2y = - 6
y = - 6/2
y = - 3


E)
x = 0
x + 3y = 5
0 + 3y = 5
3y = 5
y = 5/3

y = 0
x + 3y = 5
x + 3.0 = 5
x + 0 = 5
x = 5

x = - 1
x + 3y = 5
- 1 + 3y = 5
3y = 5 + 1
3y = 6
y = 6/3
y = 2

y = 1
x + 3y = 5
x + 3.1 = 5
x + 3 = 5
x = 5 - 3
x = 2

R.: 
Pares:

(0;5/3)
(5,0)
(-1;2)
(2;1)