Question

Resolva estes sistemas em seu caderno.

a) [x = 5y
[x + y = 2

b) [x- y = 10
[2x + 3y = 10

c) [x + y = 3
[12 x -9y= -20

d) [2x + y=7
[5x - 2y= -5

Answer 1

a)

x=5y
x+y= 2
--------
5y + y= 2
6y=2
y=2/6/2=1/3
y= 1/3

valor de x:

x+1/3=2
x=2 - 1/3
x=5/3

→ x= 5/3, y= 1/3

b)

x - y =10       ( -2)
2x + 3y= 10
-----------------
-2x +2y= - 20
2x + 3y= 10
---------- 
         5y=-10
        y = -10 /5
        y= -2

Valor de x:

x -(-2) = 10
x + 2 = 10
x= 10 -2
x= 8

→ x= 8 , y = -2

c)

x   +  y = 3         ( 9)
12x - 9y= - 20
-------------------
9x + 9y= 27
12x -9y= -20
--------------
21x=7
x=7/21/7=1/3
x=1/3

valor de y.

1/3 +  y=3
y= 3 - 1/3
y= 8/3

→ x= 8/3 , y= 1/3

d)

2x  + y = 7      (2)
5x - 2y= -5
--------------
4x +2y= 14
5x  -2y= -5
------------
9x=9
x=9/9
x=1

valor de y:

(2.1) + y = 7
2+ y = 7
y=7-2
y=5

→ x = 1 , y= 5

Espero ter ajudado
Bons Estudos :)