Question

Resolva os problemas pelo metodo de adição

1)2x-5y=2
3x+5y=28



2)x+y=7
X-y=3


3)3x+5y=11
5x-5y=5


4)2x+y=5(-1)
2x+8y=3


5)5x-4y=15(-1)
6x-4y=18

Answer 1

1)

2x-5y=2

3x+5y=28

5x = 30

x = 30/5

x = 6

2(6) -5y = 2

12 -5y = 2

-5y = -12 + 2

5y = 10

y = 2

S = (6, 2)

2)

x+y=7

x-y=3

2x = 10

x = 5

5+y = 7

y = -5+7

y = 2

S = (5, 2)

3)

3x+5y=11

5x-5y=5

8x = 16

x = 2

3(2) +5y = 11

6 + 5y = 11

5y = 11 - 6

5y = 5

y = 1

S = (2, 1)

4)2x+y=5(-1)

2x+8y=3

-2x-y= -5

2x+8y=3

7y = -2

y = $\frac{2}{7}$

2x-$\frac{2}{7}$ = 5

2x = 5 - $\frac{2}{7}$

2x = $\frac{33}{7}$

x =  $\frac{\frac{33}{7}}{2}$

x = $\frac{33}{14}$

S = (frac{33}{7}[/tex], $\frac{2}{7}$)

5)

5x-4y=15(-1)

6x-4y=18

-5x+4y=-15

6x-4y=18

x = 3

5(3) + 4y = 15

15 + 4y = 15

4y = 15-15

y = 0

S = (3, 0)

Espero ter ajudado.