SOLUTION: I have a test tomorrow, I have no clue how to graph this: Solve the system graphically: -3x + y = 7 -4x +4y +12 I got this so far : y + 3x + 7 y = x + 3 Then they want me

Algebra ->  Graphs -> SOLUTION: I have a test tomorrow, I have no clue how to graph this: Solve the system graphically: -3x + y = 7 -4x +4y +12 I got this so far : y + 3x + 7 y = x + 3 Then they want me      Log On


   

Question 687311: I have a test tomorrow, I have no clue how to graph this:
Solve the system graphically:
-3x + y = 7
-4x +4y +12
I got this so far :
y + 3x + 7
y = x + 3
Then they want me to graph it. Everyone tries to tell help me, but only makes it more confusing.
Found 2 solutions by MathLover1, stanbon:
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

Solved by pluggable solver: Solve the System of Equations by Graphing



Start with the given system of equations:


-3x%2By=7

-4x%2B4y=12





In order to graph these equations, we need to solve for y for each equation.




So let's solve for y on the first equation


-3x%2By=7 Start with the given equation



1y=7%2B3x Add 3+x to both sides



1y=%2B3x%2B7 Rearrange the equation



y=%28%2B3x%2B7%29%2F%281%29 Divide both sides by 1



y=%28%2B3%2F1%29x%2B%287%29%2F%281%29 Break up the fraction



y=3x%2B7 Reduce



Now lets graph y=3x%2B7 (note: if you need help with graphing, check out this solver)



+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+3x%2B7%29+ Graph of y=3x%2B7




So let's solve for y on the second equation


-4x%2B4y=12 Start with the given equation



4y=12%2B4x Add 4+x to both sides



4y=%2B4x%2B12 Rearrange the equation



y=%28%2B4x%2B12%29%2F%284%29 Divide both sides by 4



y=%28%2B4%2F4%29x%2B%2812%29%2F%284%29 Break up the fraction



y=x%2B3 Reduce





Now lets add the graph of y=x%2B3 to our first plot to get:


+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+3x%2B7%2Cx%2B3%29+ Graph of y=3x%2B7(red) and y=x%2B3(green)


From the graph, we can see that the two lines intersect at the point (-2,1) (note: you might have to adjust the window to see the intersection)

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Solve the system graphically:
-3x + y = 7
-4x +4y = 12
-----
Graph the 1st equation
y = 3x + 7
If x = 0, y = 7
If x = 1, y = 10
----
Plot (0,7) and (1,10) and draw a line thru them.
====================================================
Graph the 2nd equation:
!st simplify by dividing thru by -4 to get:
x - y = -3
2nd: Solve for "y":
y = x+3
---
If x = 0, y = 3
If x = 1, y = 4
----
Plot (0,3) and (1,4) and draw a line thru them.
------
graph%28400%2C400%2C-10%2C10%2C-10%2C20%2Cx%2B3%2C3x%2B7%29
-----------------
Solution is the point of intersection of the 2 lines: (-2,1)
==================
Cheers,
Stan H.