Question

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Answer 1

Resposta:

b) x + y = 8

- x + y = 6

x + y = 8

x = 8 - y

- x + y = 6

- ( 8 - y ) = 6

-8 + y = 6

- y = 6 - 8

-y = -2

y = 2

x = 8 - y

x = 8 - 2

x = 6

prova real

x + y = 8

6 + 2 = 8

8 = 8

c) 2x + y = 4

x - y = 5

x - y = 5

x = 5 + y

2x + y = 4

2 × ( 5 + y ) + y = 4

10 + 2y + y = 4

3y = 4 - 10

3y = -6

y = -6/3

y = -2

x = 5 + y

x = 5 + ( -2 )

x = 5 - 2

x = 3

prova real

x - y = 5

3 - ( - 2 ) = 5

3 + 2 = 5

5 = 5

2x + y = 4

2 × 3 + ( -2 ) = 4

6 + ( -2 ) = 4

6 - 2 = 4

4 = 4

d) x - y = 11

2x - y = 7

x - y = 11

x = 11 + y

2x - y = 7

2 ( 11 + y ) - y = 7

2 × 11 + 2 × y - y = 7

22 + 2y - y = 7

y = 7 - 22

y = -15

x = 11 + y

x = 11 + ( - 15 )

x = 11 - 15

x = -4

prova real

x - y = 11

-4 - ( - 15 ) = 11

-4 + 15 = 11

11 = 11

2x - y = 7

2 × ( -4 ) - ( -15 ) = 7

-8 + 15 = 11

11 = 11