Question

alguém me ajuda, urgente, por favor! ​

Answer 1

Resposta:

a) (3,4)

b) (3,-6)

c) (5,12)

d) (1/2,3/2)

Explicação passo-a-passo:

A)$\left \{ {{12x+8y=68} \atop {x+y=7}} \right.$

x= -y+7

12(-y+7) + 8y = 68

-12y + 84 + 8y = 68

- 4y = 68 - 84

-4y = -16

y = 16/4

y = 4

x= -(4)+7 = 3

B)$\left \{ {{6x + 4y= -6} \atop {5x - 2y = 27 (2)}} \right.$

6x + 4y = -6

10x - 4y = 54

16x = 48

x = 48/16

x = 3

6(3) + 4y = -6

18 + 4y = -6

4y = -6 - 18

4y = -24

y = - 24/4

y = -6

C)$\left \{ {{3x - y= 3} \atop {x + 2y = 29}} \right.$

-y= -3x + 3 → y = 3x - 3

x + 2(3x - 3) = 29

x + 6x - 6 = 29

7x = 29 + 6

7x = 35

x = 5

3(5) - y = 3

15 - y = 3

-y = 3 - 15

-y = -12

y = 12

D)$\left \{ {{2x + 6y=10} \atop {4x -2y = -1 (3)}} \right.$

2x+6y=10

12x-6y=-3

14x=7

x= 7/14

x= 1/2

2(1/2)+6y=10

1+6y= 10

6y= 10-1

6y= 9

y= 9/6

y= 3/2