Question

1) Resolva os sistemas abaixo.
a) {x = 54
{x + y = 12

b) { x- y = 10
{ 2x + 34 =10

c) { x + y = 3
{ 12x -9 y = -20

d) { 2x + y = 7
{ 5x -2 y = -5

e) {x + y = 6
{ 2x -y = 24

f) { x + 2y = 5
{ x + 3y = 8

g) { 3x + 4y = 19
{ 2x - 3y = 7

h) { X+ 3 y = 6
{ - 4 x + 6 y = 12

i) { V = - 1 - y
{ x - y = 0

Answer 1

a) {x = 54
{x + y = 12

x=54

x+y=12
54+y=12
y=12-54
y=42

b) { x- y = 10
{ 2x + 34 =10

2x+34=10
2x=10-34
x=-24/2
x=-12

x-y=10
-12-y=10
-y=10+12
-y=22 (-1)
y=-22

c) { x + y = 3  (9)
{ 12x -9 y = -20

9x+9y=27
12x-9y=-20

21x=7
x=7/21
x=1/3=0,333

x+y=3
0,333+y=3
y=3-0,333
y=2,667

d) { 2x + y = 7  (2)
{ 5x -2 y = -5

4x+2y=14
5x-2y=-5

9x=9
x=9/9
x=1

2x+y=7
(2 x 1)+y=7
y=7-2
y=5

e) {x + y = 6 
{ 2x -y = 24

3x=30
x=30/3
x=10

x+y=6
10+y=6
y=6-10
y=-4

f) { x + 2y = 5
{ x + 3y = 8  (-1)

x+2y=5
-x-3y=-8

-y=-3 (-1)
y=3

x+2y=5
x+(2 x 3)=5
x=5-6
x=-1

g) { 3x + 4y = 19 (-2)
{ 2x - 3y = 7        (3)

-6x-8y=-38
6x-9y=21

-y=-17 (-1)
y=17

3x + 4y = 19
3x+(4 x17)=19
3x=19-68
x= -49/3
x= -16,33



h) { X+ 3 y = 6 (-2)
{ - 4 x + 6 y = 12

-2x-6y=-12
-4x+6y=12

-6x=0
x=0

x+3y=6
0+3y=6
y=6/3
y=2

i) { x = - 1 - y
{ x - y = 0

x+y=-1
x-y=0

2x=-1
x=-1/2
x=-0,5

x+y=-1
-0,5+y=-1
y=-1+0,5
y=-0,5