SOLUTION: My worksheet says: Solve the system of equations: 3X+2Y=17 2X-Y=9 Please help thanks

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Question 161600: My worksheet says:
Solve the system of equations:
3X+2Y=17
2X-Y=9
Please help
thanks

Found 2 solutions by jim_thompson5910, Alan3354:
Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!

Start with the given system of equations:



Multiply the both sides of the second equation by 2.


Distribute and multiply.


So we have the new system of equations:



Now add the equations together. You can do this by simply adding the two left sides and the two right sides separately like this:





Group like terms.


Combine like terms. Notice how the y terms cancel out.


Simplify.


Divide both sides by to isolate .


Reduce.


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


Now go back to the first equation.


Plug in .


Multiply.


Subtract from both sides.


Combine like terms on the right side.


Divide both sides by to isolate .


Reduce.


So our answer is and .


Which form the ordered pair .


This means that the system is consistent and independent.


Notice when we graph the equations, we see that they intersect at . So this visually verifies our answer.


Graph of (red) and (green)

Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
Solve the system of equations:
3X+2Y=17 eqn 1
2X-Y=9 eqn 2
------------
2X-Y=9 eqn 2
-y = 9-2x
y = 2x-9
Sub for y into eqn 1
3x + 2(2x-9) = 17
3x + 4x -18 = 17
7x = 35
x = 5
-----------
y = 2x-9
y = 1


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