SOLUTION: Solve the following system of linear equations by graphing. x+y=9 x-y=7

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Question 691230: Solve the following system of linear equations by graphing.
x+y=9
x-y=7
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

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



Start with the given system of equations:


1x%2By=9

1x-y=7





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


1x%2By=9 Start with the given equation



1y=9-x Subtract +x from both sides



1y=-x%2B9 Rearrange the equation



y=%28-x%2B9%29%2F%281%29 Divide both sides by 1



y=%28-1%2F1%29x%2B%289%29%2F%281%29 Break up the fraction



y=-x%2B9 Reduce



Now lets graph y=-x%2B9 (note: if you need help with graphing, check out this solver)



+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+-x%2B9%29+ Graph of y=-x%2B9




So let's solve for y on the second equation


1x-y=7 Start with the given equation



-y=7-x Subtract +x from both sides



-y=-x%2B7 Rearrange the equation



y=%28-x%2B7%29%2F%28-1%29 Divide both sides by -1



y=%28-1%2F-1%29x%2B%287%29%2F%28-1%29 Break up the fraction



y=x-7 Reduce





Now lets add the graph of y=x-7 to our first plot to get:


+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+-x%2B9%2Cx-7%29+ Graph of y=-x%2B9(red) and y=x-7(green)


From the graph, we can see that the two lines intersect at the point (8,1) (note: you might have to adjust the window to see the intersection)