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Rozwiąż układ równań a) x - y = 8 i 2x + y = 2 b) y - x = 1 i x + y = 3​

Odpowiedź :

Joasia615viz

a) {x - y = 8

 {2x + y = 2

{x = 8 + y

{2(8+y) + y = 2

{x = 8 + y

{16 + 2y + y = 2

{x = 8 + y

{2y + y = 2 - 16

{x = 8 + y

{3y = -14 |:3

{y = -14/3 = -4 ⅔

{x = 8 + (-4 ⅔)

{y = -4

{x = 8 - 4 ⅔

{y = -4

{x = 3 ⅓

b) {y - x = 1

 {x + y = 3

{-x + y = 1

{x + y = 3

+______

2y = 4 |:2

y = 2

{y - x = 1

{y = 2

{y = 2

{2 - x = 1

{y = 2

{-x = 1 - 2

{y = 2

{-x = -1 |•(-1)

{y = 2

{x = 1

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