SOLUTION: The equations of two lines are given as x + 3y = 0 and 2x - y= -7. What are the coordinates of the point of intersection. How do I solve this Thank you, Natasha

Algebra ->  Systems-of-equations -> SOLUTION: The equations of two lines are given as x + 3y = 0 and 2x - y= -7. What are the coordinates of the point of intersection. How do I solve this Thank you, Natasha      Log On


   

Question 549455: The equations of two lines are given as x + 3y = 0 and 2x - y= -7. What are the coordinates of the point of intersection.
How do I solve this
Thank you,
Natasha
Answer by TutorDelphia(193) About Me  (Show Source):
You can put this solution on YOUR website!
Hi Natasha,
Finding x and y and writing them as an ordered pair (x,y) is what your teacher is looking for here.
With systems of equations there are three ways to solve it, graphing, substitution or elimination.
I'll show you elimination and graphing.
x + 3y = 0 and
2x - y= -7
Lets multiply both sides of the second equation by 3
6x-3y=-21
Now lets add the two equations
6x-3y=-21
x + 3y = 0
7x=-21
x=-3
We can then plug in -3 for x to find y
2*(-3)-y=-7
y=1
so your answer is (-3,1)
To graph we have to have the equations in slope intercept form
x + 3y = 0
3y=-x
y=-x/3

2x - y= -7
-y=-2x-7
y=2x+7
+graph%28+300%2C+300%2C+-10%2C+10%2C+-10%2C+10%2C+-x%2F3%2C+2x%2B7%29+
and we see they intersect at (-3,1)