Question

alguém responde por favor, vale 10 pontos (é pra 20:00)

Answer 1

Resposta:

   p)

x = y = 1.

   q)

x = 4; y = -1.

   r)

x = 11/3; y = 5/3.

   s)

x = 2; y = 3.

   t)

x = 1; y = 2.

   u)

x = 6; y = 9.

   v)

x = 3; y = 1.

   w)

x = 14/9; y = 40/9.

   x)

x = 1; y = 2.

Explicação passo-a-passo:

   p)

$\left \{ {{2x - 4y=-2} \atop {5x-3y=2}} \right.$

2x = -2 + 4y

2x = 2(-1 + 2y)

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

x = 2y - 1.

5(2y - 1) - 3y = 2

10y - 5 - 3y = 2

7y = 2 + 5

7y = 7

y = 7/7

y = 1.

x = 2×1 - 1

x = 2 - 1

x = 1.

   q)

$\left \{ {{3x + 5y=7} \atop {2x-3y=11}} \right.$

3x + 5y = 7

3x = 7 - 5y

x = (7 - 5y)/3

2x - 3y = 11

2x = 11 + 3y

x = (11 + 3y)/2

(7 - 5y)/3 = (11 + 3y)/2

2×(7 - 5y)/6 = 3×(11 + 3y)/6

14 - 10y = 33 + 9y

-10y - 9y = 33 - 14

- 19y = 19

y = 19/-19

y = -1.

x = (7 - 5y)/3

x = (7 - 5×(-1))/3

x = (7 + 5)/3

x = 12/3

x = 4.

   r)

$\left \{ {{x=y-2} \atop {2x+y=1}} \right.$

x = y - 2

2(y - 2) + y = 1

2y - 4 + y = 1

3y = 1 + 4

3y = 5

y = 5/3.

x = 2 + y

x = 2 + 5/3

x = 6/3 + 5/3

x = (6 + 5)/3

x = 11/3.

   s)

$\left \{ {{3x-y=3} \atop {4y=12}} \right.$

4y = 12

y = 12/4

y = 3.

3x - y = 3

3x - 3 = 3

3x = 3 + 3

3x = 6

x = 6/3

x = 2.

   t)

$\left \{ {{4x =2y} \atop {2x+3y=8}} \right.$

4x = 2y

y = 4x/2

y = 2x

2x + 3(2x) = 8

2x + 6x = 8

8x = 8

x  = 8/8

x = 1.

y = 2x

y = 2×1

y = 2.

   u)

$\left \{ {{7x-3y=6} \atop {2x=y+3}} \right.$

7x - 3y = 6

7x = 6 + 3y

x = (6 + 3y)/7

2x = y + 3

x = (y + 3)/2

(6 + 3y)/7 = (y + 3)/2

2×(6 + 3y)/14 = 7×(y + 3)/14

12 + 6y = 7y + 21

7y - 6y = 21 - 12

y = 9.

x = (y + 3)/2

x = (9 + 3)/2

x = 12/2

x = 6.

   v)

$\left \{ {{x-y-2=0} \atop {2x+y=7}} \right.$

x - y - 2 = 0

x = y + 2

2(y + 2) + y = 7

2y + 4 + y = 7

3y = 7 - 4

3y = 3

y = 3/3

y = 1.

x = y + 2

x = 1 + 2

x = 3.

   w)

$\left \{ {{x+y=6} \atop {10x+y=20}} \right.$

x = 6 - y

10(6 - y) + y = 20

60 - 10y + y = 20

-9y = 20 - 60

-9y = -40

y = -40/-9

y = 40/9.

x = 6 - y

x = 6 - 40/9

x = 54/9 - 40/9

x = 14/9.

   x)

$\left \{ {{y=4-2x} \atop {5x-2y=1}} \right.$

y = 4 - 2x

5x - 2(4 - 2x) = 1

5x - 8 + 4x = 1

9x = 1 + 8

9x = 9

x = 9/9

x = 1.

y = 4 - 2x

y = 4 - 2×1

y = 4 - 2

y = 2.

   Espero ter ajudado...