SOLUTION: Solve the system by graphing. x – 2y = 8 x + y = –1 REALLY NEED HELP GRAPHING!

Algebra ->  Graphs -> SOLUTION: Solve the system by graphing. x – 2y = 8 x + y = –1 REALLY NEED HELP GRAPHING!      Log On


   

Question 124718: Solve the system by graphing.
x – 2y = 8
x + y = –1
REALLY NEED HELP GRAPHING!
Found 2 solutions by jim_thompson5910, checkley71:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

Start with the given system of equations:

1x-2y=8
1x%2By=-1




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-2y=8 Start with the given equation


-2y=8-x Subtract +x from both sides


-2y=-x%2B8 Rearrange the equation


y=%28-x%2B8%29%2F%28-2%29 Divide both sides by -2


y=%28-1%2F-2%29x%2B%288%29%2F%28-2%29 Break up the fraction


y=%281%2F2%29x-4 Reduce


Now lets graph y=%281%2F2%29x-4 (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+%281%2F2%29x-4%29+ Graph of y=%281%2F2%29x-4



So let's solve for y on the second equation

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


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


1y=-x-1 Rearrange the equation


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


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


y=-x-1 Reduce



Now lets add the graph of y=-x-1 to our first plot to get:

+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+%281%2F2%29x-4%2C-x-1%29+ Graph of y=%281%2F2%29x-4(red) and y=-x-1(green)

From the graph, we can see that the two lines intersect at the point (2,-3) (note: you might have to adjust the window to see the intersection)

Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
x-2y=8 or -2y=-x+8 or y=-x/-2+8/-2 or y=x/2-4 (red line)
x+y=-1 or y=-x-1 (green line)
The answer is (2,-3)
+graph%28+300%2C+200%2C+-6%2C+5%2C+-10%2C+10%2C+y+=+x%2F2+-4%2C+y+=+-x+-1%29+ (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, of TWO functions y = x/2 -4 and y = -x -1).