SOLUTION: I don;t get this graphing thing at all! I have to solve the system of linear equations by graphing: 3x-y=0 6x+y=9 Can someone help me? or point towards a site that will graph it

Question 746844: I don;t get this graphing thing at all! I have to solve the system of linear equations by graphing:
3x-y=0
6x+y=9
Can someone help me? or point towards a site that will graph it and show me how? I have a test on this on Sunday and have been working on it all week. I don;t get it!
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
solve the system of linear equations by graphing:
3x-y=0
6x+y=9
This is not that hard, we will take one equation at a time, rearrange
equation to the slope/intercept form which is y = mx + b
3x - y = 0
Subtract 3x from both sides
-y = -3x + 0
y has to be positive, multiply both sides by -1, we can ignore 0, obviously
y = 3x is the equation we can graph, Choose at least two value for x and find y
a table
x | y
-------; Calculation of y using the x values
-3 |-9; (y = 3(-3); y=-9
-1 |-3; (y = 3(-1); y=-3
+2 |+6; (y = 3(2); y= 6
Plot these x,y pair, the graph is the straight line thru these points
looks like this

:
Do the same thing with the 2nd equation
6x + y = 0
subtract 6x from both sides
y = -6x
Chose 3 values for these, can be same if you wish
x | y
-------
-3 |+18; (y = -6(-3); y=+18
-1 |+6; (y = -6(-1); y=+6
+2 |-12; (y = -6(2); y= -12
Plot these x,y pair, the graph is the straight line thru these points
looks like this, (added it to the graph made of the first equation)

:
The solution is the point of intersection, x,y pairs are 0,0 for both equations at this point.
:
Did this make sense to you? Any questions?
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