SOLUTION: Please help. I don't understand this. Solve the following system by substitution. If a unique solution does not exist, state whether the system is inconsistent or dependent. 4x

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: Please help. I don't understand this. Solve the following system by substitution. If a unique solution does not exist, state whether the system is inconsistent or dependent. 4x      Log On


   

Question 54435: Please help. I don't understand this.
Solve the following system by substitution. If a unique solution does not exist, state whether the system is inconsistent or dependent. 4x – 12y = 5 and -x + 3y = -1
Answer by funmath(2933) About Me  (Show Source):
You can put this solution on YOUR website!
L1) 4x-12y=5
L2) -x+3y=-1
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Solve L2) for x because that's the easiest one in which to isolate a variable.
-x+3y=-1
-x+3y-3y=-3y-1
-x=-3y-1
-(-x)=-(-3y-1)
x=3y+1
Substitute this value for x in L1) and solve for y.
4(3y+1)-12y=5
12y+4-12y=5
(12-12)y+4=5
0+4=5
4=5
We can't solve for y and 4 does not = 5, so this system is:highlight%28inconsistent%29. It has no solution because the lines have no points in common. Graphically, they would be parallel lines that never intersect.
If we got something that could not be solved for y but was true like 0=0 that would be dependent.
Happy Calculating!!!