Question

Resolva cada sistema abaixo:
a)2x-y=30
3x-4y=5

b)x+y=30
X+y=5

c)2x+y=-30
X-y=5

d)2x+y=30
3x-4y=5

Answer 1

Explicação passo-a-passo:

a)

(2x-y=30 => -y=30-2x

(3x-4y=5

3x-4(30-2x)=5

3x-120+8x=5

11x=5+120

11x=125

x=125/11

3x-4y=5

3.(125/11)-4y=5

y=80/11

b)

(x+y=30×(-1)

(X+y=5

:

(-x-y=-30

(x+y=5

=======

0

c)

(2x+y=-30

(X-y=5

========(+)

3x=-25

x= -25/3

2x+y= -30

2(-25/3)+y= -30

y= - 40/3

d)

(2x+y=30. × (4)

(3x-4y=5

:

:

(8x + 4y=120

(3x-4y=5

==========(+)

11x=125

x=125/11

y=80/11