+0  
 
-5
210
1
avatar+60 

Solve the following system:

 Apr 22, 2019
 #1
avatar+106533 
+2

x + 2y  = 4    (1) 

2x - y  = -7  ⇒   y  = 2x + 7   ( 2)

 

Sub (2) into (1)  for y

 

x + 2 [2x + 7]  = 4

x + 4x + 14  = 4

5x + 14  = 4      subtract 14 from both sides

5x = -10            divide both sides by 5         

x = -2

 

So....using (2).....y  = 2(-2) + 7  =  3

 

So....the last equation becomes

 

-2 + 3 + z  = - 4

1 + z  = -4      subtract 1 from both sides

z  = - 5

 

{x, y, z }  =  { -2, 3, - 5}

 

 

 

 

cool cool cool

 Apr 22, 2019

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