SOLUTION: Solve the system of equations by graphing. Then classify the system 3x - 9y = 81 2x - 6y = -4 I came up with (6,7) (3,7) I don't undertand this stuff though.

Algebra ->  Graphs -> SOLUTION: Solve the system of equations by graphing. Then classify the system 3x - 9y = 81 2x - 6y = -4 I came up with (6,7) (3,7) I don't undertand this stuff though.      Log On


   

Question 206974: Solve the system of equations by graphing. Then classify the system
3x - 9y = 81
2x - 6y = -4
I came up with (6,7)
(3,7)
I don't undertand this stuff though.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

Start with the given system of equations:


system%283x-9y=81%2C2x-6y=-4%29


In order to graph these equations, we must solve for y first.


Let's graph the first equation:


3x-9y=81 Start with the first equation.


-9y=81-3x Subtract 3x from both sides.


y=%2881-3x%29%2F%28-9%29 Divide both sides by -9 to isolate y.


y=%281%2F3%29x-9 Rearrange the terms and simplify.


Now let's graph the equation:


Graph of y=%281%2F3%29x-9.


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


Now let's graph the second equation:


2x-6y=-4 Start with the second equation.


-6y=-4-2x Subtract 2x from both sides.


y=%28-4-2x%29%2F%28-6%29 Divide both sides by -6 to isolate y.


y=%281%2F3%29x%2B2%2F3 Rearrange the terms and simplify.


Now let's graph the equation:


Graph of y=%281%2F3%29x%2B2%2F3.


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


Now let's graph the two equations together:


Graph of y=%281%2F3%29x-9 (red). Graph of y=%281%2F3%29x%2B2%2F3 (green)


From the graph, we can see that the two lines are parallel, which means that they will never intersect.


So there are no solutions. This means that the system of equations is inconsistent.