SOLUTION: Please help. Solve the system by graphing. 3x + y = -1 9x +3y = -3 Thanks JMS

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Question 115291: Please help.
Solve the system by graphing.
3x + y = -1
9x +3y = -3
Thanks
JMS

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!
I'm going to assume that you know how to graph a line. If that isn't true, write back and we can talk more about that part.

Solving a system of linear equations in two variables means that you have two equations that each represent a line. The solution to the system is the point where the two lines intersect. This is the graphical analogue of knowing the x and y coordinates of the intersection point and those x and y values would make both of the equations true statements. The only fly in the ointment is that sometimes you have parallel lines that never intersect meaning there is no solution, and sometimes you have co-incident lines meaning that there are an infinite number of solutions. (You will see that this is the case here)

The quickest way to graph a line is to put it into slope-intercept form:

y=mx%2Bb

3x%2By=-1
y=-3x-1, so the slope is -3 and the y-intercept is -1

9x%2B3y=-3
3y=-9x-3
y=-3x-1, same equation, same line, infinite solutions.

graph%28400%2C+400%2C+-5%2C5%2C-5%2C5%2C-3x-1%2C-3x-1%29