Question

5x-8y=4
-5x+10y=0
resolver sistema modo substituição
-6x+2y=4
4x+y= -5

Answer 1

a)

  5x - 8y = 4
- 5x + 10y = 0

5x = 4 + 8y
x = 4 + 8y
         5

- 5x + 10y = 0
10y = 5x
10y = 5.(4 + 8y)
                5

10y = 4 + 8y
10y - 8y = 4
2y = 4
y = 4/2
y = 2

- 5x + 10y = 0
10y = 5x
10.2 = 5x
20 = 5x
5x = 20
x = 20/5
x = 4

Resp.: x = 4 e y = 2
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b)
- 6x + 2y = 4
  4x + y = - 5

4x + y = - 5
y = - 5 - 4x

- 6x + 2y = 4
- 6x + 2.(- 5 - 4x) = 4
- 6x - 10 - 8x = 4
- 14x = 4 + 10
- 14x = 14 ( - 1)
14x = - 14
x = -14/14
x = - 1

y = - 5 - 4x
y = - 5 - 4.(-1)
y = - 5 + 4
y = - 1

Resp.: x =  - 1 e y = - 1