SOLUTION: 3x+y=9 5x-y=7 Solve the system of equation by graphing Im confused becasue how can they just pick numbers?? Please Help thanks!

Algebra ->  Linear-equations -> SOLUTION: 3x+y=9 5x-y=7 Solve the system of equation by graphing Im confused becasue how can they just pick numbers?? Please Help thanks!      Log On


   

Question 719859: 3x+y=9
5x-y=7
Solve the system of equation by graphing
Im confused becasue how can they just pick numbers?? Please Help thanks!
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+3x+%2B+y+=+9+
+5x+-+y+=+7+
First put them both into the same form
(1) +y+=+-3x+%2B+9+
(2) +y+=+5x+-+7+
-----------------
The slope of (1) is +-3+
The slope of (2) is +5+
----------------------
The point where the lines intersect is
the solution of the equations
To find the solution:
Add the equations as they are given originally
+3x+%2B+y+=+9+
+5x+-+y+=+7+
+8x+=+16+
+x+=+2+
PLug this result back into either equation
+3%2A2+%2B+y+=+9+
+y+=+9+-+6+
+y+=+3+
------------
This tells me the intersection is at ( 2,3 )
Here's the graph:
+graph%28+400%2C+400%2C+-5%2C+5%2C+-10%2C+10%2C+-3x+%2B+9%2C+5x+-+7+%29+