SOLUTION: Please help I am getting confused...I need to solve each system by the substitution method. {{{x+3y=2}}} first {{{-x+y=1}}} second thanks so much

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Question 124955: Please help I am getting confused...I need to solve each system by the substitution method.
first
second
thanks so much

Found 2 solutions by iluvbuilding429, jim_thompson5910:
Answer by iluvbuilding429(41)   (Show Source): You can put this solution on YOUR website!
Please help I am getting confused...I need to solve each system by the substitution method.
first
second
thanks so much


Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
We'll use substitution. After moving 3*y to the right, we get:
, or . Substitute that
into another equation:
and simplify: So, we know that y=0.75. Since , x=-0.25.

Answer: .

Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!


Start with the given system of equations:





Now in order to solve this system by using substitution, we need to solve (or isolate) one variable. I'm going to solve for y.




So let's isolate y in the first equation

Start with the first equation


Subtract from both sides


Rearrange the equation


Divide both sides by


Break up the fraction


Reduce



---------------------

Since , we can now replace each in the second equation with to solve for



Plug in into the first equation. In other words, replace each with . Notice we've eliminated the variables. So we now have a simple equation with one unknown.



Multiply both sides by the LCM of 3. This will eliminate the fractions (note: if you need help with finding the LCM, check out this solver)



Distribute and multiply the LCM to each side



Combine like terms on the left side


Subtract 2 from both sides


Combine like terms on the right side


Divide both sides by -4 to isolate x



Reduce





-----------------First Answer------------------------------


So the first part of our answer is:









Since we know that we can plug it into the equation (remember we previously solved for in the first equation).



Start with the equation where was previously isolated.


Plug in


Multiply


Combine like terms and reduce. (note: if you need help with fractions, check out this solver)



-----------------Second Answer------------------------------


So the second part of our answer is:









-----------------Summary------------------------------

So our answers are:

and

which form the point








Now let's graph the two equations (if you need help with graphing, check out this solver)


From the graph, we can see that the two equations intersect at . This visually verifies our answer.




graph of (red) and (green) and the intersection of the lines (blue circle).




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