Question

Resolva pelo metodo da substituição
A)3x+y=5
4x+3y=10
B)5x+6y=21
X+7y=10
C)3x-2y=-5
4x+5y=1
D)x+y=1
2x+3y=4

Answer 1

Resposta:

a) (x,y)= (1,2)

b) (x,y)= (3,1)

c) (x,y)= (-1,1)

d) (x,y)= (-1,2)

Explicação passo-a-passo:

a)

{3x+y=5

{4x+3y=10

↓

{y=5-3x

{4x+3y=10

↓

4x+3(5-3x)=10

↓

x=1

↓

y=5-3•1

↓

y=2

↓

(x,y)= (1,2)

b)

{5x+6y=21

{x+7y=10

↓

{5x+6y=21

{x=10-7y

↓

5(10-7y)+6y=21

↓

y=1

↓

x=10-7•1

↓

x=3

↓

(x,y)= (3,1)

c)

{3x-2y= -5

{4x+5y=1

↓

{x= -5/3 +2/3 y

{4x+5y=1

↓

4(-5/3 +2/3 y)+5y=1

↓

y=1

↓

x= -5/3 +2/3 •1

↓

x= -1

↓

(x,y)= (-1,1)

d)

{x+y=1

{2x+3y=4

↓

{x=1-y

{2x+3y=4

↓

2(1-y)+3y=4

↓

y=2

↓

x=1-2

↓

x= -1

↓

(x,y)= (-1,2)