SOLUTION: Please help me solve this system by substitution? { 2x - y = 4 { y = 2x - 4

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Question 688349: Please help me solve this system by substitution? { 2x - y = 4
{ y = 2x - 4
Answer by MathLover1(20850)   (Show Source): You can put this solution on YOUR website!

........1
..........2
__________________
......1....solve for
.......substitute in 2
________________________
..........2....solve for

............. there are an infinite number of solutions and the
system is

check it graphically:
........1
..........2
__________________
........1
..........2
____________________________

Solved by pluggable solver: Solve the System of Equations by Graphing



Start with the given system of equations:










In order to graph these equations, we need to solve for y for each equation.




So let's solve for y on the first equation


Start with the given equation



Subtract from both sides



Rearrange the equation



Divide both sides by



Break up the fraction



Reduce



Now lets graph (note: if you need help with graphing, check out this solver)



Graph of




So let's solve for y on the second equation


Start with the given equation



Add to both sides



Rearrange the equation



Divide both sides by



Break up the fraction



Reduce





Now lets add the graph of to our first plot to get:


Graph of (red) and (green)


From the graph, we can see that the two lines are identical (one lies perfectly on top of the other) and intersect at all points of both lines. So there are an infinite number of solutions and the system is dependent.
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