Question 63064This question is from textbook  
:  Solve the following systems by addition. If a unique solution does not exist, state whether the system is inconsistent or dependent. 
x + 5y = 10 
-2x - 10y = -20 
 
This question is from textbook  
 Answer by funmath(2933)      (Show Source): 
You can  put this solution on YOUR website! Solve the following systems by addition. If a unique solution does not exist, state whether the system is inconsistent or dependent. 
E1:  x + 5y = 10 
E2:  -2x - 10y = -20 
Multiply E1 by 2 and add it to E2. 
E1:  2(x+5y)=2(10) --> 2x+10y=20 
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2x+10y=20 
-2x-10y=-20 
____________ 
0+0=0 
0=0 
When all your variables are eliminated, you have one of two cases, 0=0 means that the system is dependent.  The lines are lying right on top of each other and there are infinitely many solutions because they have all points in common. 
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If both your variables are eliminated and your left with 0=(something other than 0).  Then you would have had an inconsitent system.  The lines would be parallel and never intersect, thus giving no solution. 
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Happy Calculating!!! 
 
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