Question

Resolva os sistemas

a) {x=5y
{x +y = 12


b){x - y = 10
{2x+ 3y = 10


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

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

Answer 1

Resposta:

A) x=10 e y = 12

B) x = 8 e y = - 2

C) x = 1/3 e y = 8/3

D) x = 1 e y = 5

Explicação passo-a-passo:

A){x = 5y

{x+y =12

{x = 5y

{5y + y =12

{x = 5y

{y = 12/6

{x = 5*2

{y = 2

{x = 10

{y = 2

B) {x - y = 10

{2x + 3y = 10

{x = 10 + y

{2(10 + y) + 3y = 10

{x = 10 + y

{20 + 5y =10

{x = 10 + y

{y = (10-20)/5

{x = 10 + y

{y = - 2

{x = 10 + (-2)

{y = - 2

{x = 8

{y = - 2

C) {x + y = 3

{12x - 9y = - 20

{x = 3 - y

{12(3-y) - 9y = - 20

{x = 3 - y

{36 - 12y - 9y = - 20

{x = 3 - y

{-21y = - 20 - 36

{x = 3 - y

{y = 56/21

56/21 = 8/3

{x = 3 - 8/3

{y = 8/3

{x = 1/3

{y = 8/3

D) {2x + y = 7

{5x - 2y = - 5

{x = (7-y)/2

{5((7-y)/2) - 2y = - 5

Multiplicamos todas as bases por 2

{x = (7-y)/2

{35 - 5y - 4y = - 10

{x = (7-y)/2

{-9y = - 45

{x = (7-y)/2

{y = 45/9 = 5

{x = (7-5)/2

{y = 5

{x = 2/2 = 1

{y = 5

Answer 2

Resposta:

1/2 -2/3

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