Question

Coomo resolver esses sistemas b) x+2y=12 3x-y=22 c)-2x-6=6 x+7y=-3 d)5x-y=1 2x-3y=-10 e) x+8y=-14 2x-9y=-3

Answer 1

b) x+2y=12  ----> x = 12-2y
    3x-y= 22 

3(12-2y)-y=22
36-6y-y=22
-7 = 22-36
-7y= -14
   y = -14 / -7
   y= 2 , x= 8


 c)-2x-6=6
    x+7y=-3 ----> x= -3-7y 

-2(-3-7y)-6 = 6 
6+14y - 6 = 6
    14y=6 
      y = 14/6 = 7/3 

d)5x-y=1  ----> -y=1-5x -----> y = -1+5x
   2x-3y=-10 

2x - 3(-1+5x) = -10 
2x +3 -15x = -10
-13x = -13
      x= 1, y= 4

 e) x+8y=-14 -----> x = -14-8y
     2x-9y=-3

     2(-14-8y)-9y =-3  
   -28-16y-9y=-3
       -25y = 25
            y = -1 , x= -6