Question

a) 3×-2y=14
5×+3y=17

b) ×+y=2
×+2y=7

c) a+2b=7
3a+b=4

d) 3×-2y=14
4×+3y=-4​

Answer 1

Resposta:

Explicação passo-a-passo:

A)

3×-2y=14 (3)

5×+3y=17 . (2)

9x - 6y = 42

10x + 6y = 34 (+)

-------------------------

19x = 76

x = 76/4

x = 4

5x + 3y = 17

5.4 + 3y = 17

20+3y = 17

3y = 17 - 20

3y = - 3

y = - 3/3

y = - 1

R.: x = 4; y = - 1

b)

×+y=2 (-2)

×+2y=7

- 2x - 2y = - 4

x + 2y = 7 (+)

-----------

- x = 3 (-1)

x = - 3

x+ y = 2

- 3 + y = 2

y = 3 + 2

y = 5

R.:

x = - 3; y = 5

c)

a+2b=7

3a+b=4 (-2)

a + 2b = 7

- 6a - 2b = - 8 (+)

------------------

- 5a = - 1 (-1)

5a = 1

a = 1/5

a + 2b = 7

1/5 + 2b = 7

2b = 7 - 1/5

5.2b/5 = (5.7 - 1)/5

10b = 35 - 1

(:2) 10b = 34 (:2)

5b = 17

b = 17/5

R.: a = 1/5; b = 17/5

d)

3×-2y=14 .(3)

4×+3y= -4​ .(2)

9x - 6y = 42

8x + 6y = - 8 (+)

----------------

17x = 34

x = 34/17

x = 2

3x - 2y = 14

3.2 - 2y = 14

6 - 14 = 2y

- 8 = 2y

2y = - 8

y = - 8/2

y = - 4

R.: x = 2; y = - 4