Question

Resolva os sistemas:

a) {x+3y=30

{y=3x


b) {3x-y=1

{4x+y=20

Answer 1

A) Substituindo “y” (já que y=3x)
x + 3.3x = 30
x + 9x = 30
10x = 30
x = 30/10 = 3

Answer 2

Explicação passo-a-passo:

A)

{x+3y=30

{y=3x

x+3y=30

x+3(3x)=30

x+9x=30

10x=30

x=30 ÷10

x= 3

y=3x

y=3(3)

y=9

B)

{3x-y=1 x=(1+y)/3

{4x+y=20

4x+y=20

4(1+y)/3 + y =20

4+4y/3 + y = 20

(MMC 3,1 = 3)

4+4y + 3y = 60

4+ 7y= 60

7y= 60 - 4

7y= 56

y= 56 ÷ 7

y= 8

x= (1+y)/3

x= (1+(8))/3

x= 9/3

x= 3