WHO KNOWS HOW TO SOLVE SYSTEMS BY GRAPHING NEED HELP

Question

terenzreignz · Answer

Well, keep in mind that the accuracy of your answer will depend greatly on your care in drawing... I myself don't possess that ability XD

That said, all you need to do is to know how to graph lines on a Cartesian plane.  You already got that covered?

anonymous · Answer

noo i have no clue how to graph! well not these kinda graphs

terenzreignz · Answer

Okay, maybe we'd do best if you give me an example... something to work with, and we'll do it together.  One from your book would be nice

anonymous · Answer

ok so its y=2x+4
y=x+2

terenzreignz · Answer

Okay, importantly, I need you to follow on while doing this yourself, on a carefully drawn cartesian plane, drawn to scale, preferably, is that all right?

anonymous · Answer

yes but what do you mean by draw a scale

terenzreignz · Answer

I mean drawn to scale, say, one cm = 2 units, or something like that, as long as it's precise.

anonymous · Answer

im so confused is there anyway you can break it down more

terenzreignz · Answer

Okay, let's go on ahead, anyway :D
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Say this is your Cartesian Plane.

anonymous · Answer

ok

terenzreignz · Answer

We graph this line:
y = 2x + 4
by identifying its intercepts.  
The x-intercept is where the line intersects the x-axis
The y-intercept is where the line intersects the y-axis

So, to find an x intercept, set y = 0
And solve for x
0 = 2x + 4
x = -2

To find a y-intercept, set x = 0 instead
And solve for y
y = 2(0) + 4
y = 4

So, our x intercept is (-2, 0)
While our y intercept is (0, 4)

Locate these points on the plane

terenzreignz · Answer

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anonymous · Answer

ok

terenzreignz · Answer

And then, just connect the two points...|dw:1359471354557:dw|

terenzreignz · Answer

And this is your first line.  Can you graph the second?

anonymous · Answer

i am so bad at this!!

terenzreignz · Answer

Just practice with them.  Also, your second line, y = x + 2
If we take its y-intercept, (set x = 0)
You get
y = 0 + 2
y = 2
Now take its x-intercept (set y = 0)
0 = x + 2
x = -2

And we have our intercepts
(0, 2) and (-2, 0)
We locate these points once again...

terenzreignz · Answer

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Note that we already found the point (-2, 0) earlier, it's still marked, even.

anonymous · Answer

ohh okay i think its making sense!!

terenzreignz · Answer

Once again, connect the intercepts...
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terenzreignz · Answer

Now, you can (crudely) see that the two lines intersect at (-2, 0)
So that's your solution to the system.
x = -2
y = 0

anonymous · Answer

OH!!!

terenzreignz · Answer

heh
:)