Question

SISTEMAS DE EQUAÇÕES DO 1º GRAU

1) 7X - 15Y = -21
X+Y = -3

2) X+2Y = 14
X+4Y = -30

3) X-Y = -2
X-Y = -6

Answer 1

1) 7X - 15Y = -21
       X+Y = -3 (x-7)
7x-15y=-21
-7x -7y = 21
22y=0
y=0

7x= -21
x=-21/7
x=-3

2) X+2Y = 14 (x-1)
    X+4Y = -30
-x-2y=-14
x+4y=-30
2y=-44
y= -44/2
y= -22

x+2.-22= 14
x - 44= 14
x= -30

3) X-Y = -2
    X-Y = -6
??????????

Answer 2

1)

7x - 15y= - 21
x + y= -3        ( -7)
--------------
7x - 15y= -21
-7x - 7y= 21
----------
        -21y=0
        21y=0
        y=0/21
        y= 0

valor de x:

x +0= -3
x= -3 
 
→ x = -3 , y = 0

2)

x+2y=14      (-1)
x+4y= - 30  
---------------------
-x -2y= -14
x+ 4y= -30
   2y= - 44
    y= -44/2
    y= -22

valor de x:

x +(2.-22)=14
x +(-44)=14
x-44=14
x=14 + 44
x=58

→ x = 58 , y= -22

3)
x- y= -2
x +y= -6
-----------
2x=-8
x=-8/2
x= -4

valor de y:

- 4 + y= -6
y=-6 +4
y= -2

→x= -4 , y = -2

Bons Estudos :)