Question

Resolva utilizando o método da comparação
x+y=5
x-y=9

2) 3x-2y=7
4x+y = 13

x-2y=4
5x -y=2

Answer 1

1) x + y = 5

x - y = 9

2x = 14

x = 14/2

x = 7

7 + y = 5 => y = 5 - 7 => y = -2

2) 3x - 2y = 7

4x + y = 13   * (2)

8x + 2y = 26

11x = 33 => x = 33/11 => x = 3

(4 * 3) + y = 13

y = 13 - 12 => y = 1

3) x - 2y = 4

5x - y = 2   * (-2)

-10x + 2y = -4

-10x = 0 => x = 0/-10 => x = 0

5 * 0 - y = 2

-y = 2  * (-1)

y = -2