Question

Resolva os sistemas
1 ) x + y = 30
x - y = 6

2 ) 4x + 5y = -6
3x + 2y = -1

3 ) y = 5x - 3
x + 3y = 7

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

Answer 1

Vamos là.

1)

x + y = 30

x - y = 6

2x = 36

x = 18, y = 12

S = (18, 12)

2)

4x + 5y = -6

3x + 2y = -1

12x + 15y = -18

12x + 8y = -4

7y =-14

y = -2

4x - 10 = -6

4x = 4

x = 1

S = (1, -2)

3)

5x - y = 3

x + 3y = 7

15x - 3y = 9

16x = 16

x = 1

1 + 3y = 7

3y = 6

y = 2

S = (1, 2)

4)

4x - 5y = 1

x - y = 1

5x - 5y = 5

-x = -4

x = 4

4 - y = 1

y = 3

S = (4, 3)