What quadrant are the equations in?
A. 3x + 2y = -15
x - 4y = -20
B. 10x - y = -30
x - y = -2
C. 2x - 5y = 10
x + 2y = 10
D. 3x + y = 9
-7x - 7y = -14

- anonymous

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- katieb

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- anonymous

http://lhh.tutor.com/presession.aspx?ProgramGUID=c2f98cc5-be2f-42f3-abbd-891c960a6bd5&TopicId=1&InterfaceId=k12&InterfaceType=k12

- anonymous

go there for some accuarate help

- anonymous

I don't have a library card #. That's not going to help me.

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## More answers

- anonymous

240100447204

- anonymous

try that

- anonymous

lemme know what happens

- anonymous

It worked but I don't see it helping me too much.

- anonymous

ok you shouldve pressed the math section

- anonymous

I did.

- anonymous

ok then you fill out the information on the bottom it shouldve let you type in your qestion

- anonymous

Would this be algebra I or II?

- anonymous

algebra 2

- anonymous

What subtopic?

- anonymous

what are your choices

- anonymous

would it be graphing functions?

- anonymous

yes

- anonymous

I just need to know how to graph them.

- anonymous

girl go the bottom of tha page and get a tutor a live tutor will help you out

- anonymous

I don't like that site.

- anonymous

lol ok then well their helpful i jsut uesd them rite now and they gave me the rite answer to everyting

- anonymous

Brizy, here's something else you can also try. Go to http://fooplot.com. It will graph the equations for you and you can see what quadrants they are in.
You do have to solve for y first. So your first equation in A would be:
3x + 2y = -15
2y = -3x - 15
y = (-3/2)x - (15/2)
Then you'd enter everything right of the "=" sign on that website. Hope that helps.

- anonymous

now thats coool im gonna try that

- anonymous

Yeah that seems complicated :-(

- anonymous

my god girl you are hard to please

- anonymous

Lol I've herd that before :-)

- anonymous

Haha. It does take some work, but that process should at least make it easier.

- anonymous

ya try it

- anonymous

oh shadowfiend was here

- shadowfiend

Still is.

- anonymous

aaaaahhhhhh

- anonymous

have i metntioned you look wonderful today:)

- shadowfiend

BrizyBabyâ€”the easiest way to answer these question is usually to graph them, honestly.

- anonymous

I don't know how to graph the equations....that's what I need help with.

- shadowfiend

Got it! Now we're at the heart of the problem :)

- shadowfiend

Let's start with A then. We have two equations:
3x + 2y = -15
x - 4y = -20

- anonymous

well i give up nice meeting you thoug Brizzy

- anonymous

I need a easy way to know how to graph them.

- anonymous

You too aminah.love18

- shadowfiend

I find it easiest to graph equations when they're in y = mx + b (slope-intercept) form. So first things first, we try to solve the equations for y:
\[\begin{align}
3x + 2y &= -15\\
2y &= -3x - 15\\
y &= \frac{-3x - 15}{2} = -\frac{3}{2}x - \frac{15}{2}
\end{align}\]
And the other one:
\[\begin{align}
x - 4y &= -20\\
-4y &= -20 - x\\
y &= \frac{-20 - x}{4} = \frac{-20}{4} - \frac{1}{4}x\\
y &= -5 - \frac{1}{4}x = -\frac{1}{4}x - 5
\end{align}\]

- shadowfiend

So, we now have:
y = -3/2 x - 15/2
y = -1/4x - 5
The first thing to notice is that both of these have a negative slope. Do you know what a negative slope means on a graph?

- anonymous

I don't get how you did the equations but yeah a negative slope goes down left to right.

- shadowfiend

Whoops. Sorry then, let's go back to that :)
Let's start with 3x + 2y = -15. We're trying to solve for y. That means we need y alone.
Remember that an equation doesn't change if we subtract the same thing from both sides. So first things first, we move the 3x to the right:
3x + 2y = -15
3x - 3x + 2y = -15 - 3x
Subtract 3x from both sides, 3x - 3x is 0:
0 + 2y = -15 - 3x
2y = -15 - 3x
(We leave off the 0.) Then we need to get rid of the 2. Dividing the same thing from both sides also leaves the equation unchanged, so we'll divide by 2:
y = (-15 - 3x) / 2
y = -15/2 - 3/2 x
Does that make more sense?

- anonymous

yeah. So the points are -7.5 and -1.5?

- shadowfiend

Close! :)
This means that the line is, like we said, going top left to bottom right. It means for every 3 units down that it goes, it goes two units to the right. And it means that it meets the y axis at -7.5. A quick, semi-accurate drawing:
|dw:1329863330467:dw|

- anonymous

What did I get wrong?

- shadowfiend

So you can see here that that line is in quadrants II, III, and IV:
|dw:1329863470553:dw|

- shadowfiend

-1.5 isn't a point, it's the slope, that's all.

- anonymous

So, it's in the third Quadrant?

- shadowfiend

Well, that's what I'm not 100% clear on in the question. Obviously this line goes through three quadrants. Is the question asking which quadrant both lines are in or..?

- anonymous

Well does it mean what quadrant the slope is in?

- shadowfiend

Sorry -> slope isn't really in a quadrant. It just tells you how the line moves from one position to another (i.e., what angle it's at).

- shadowfiend

It probably means what quadrant the two lines meet in, so let's look at the other line.

- shadowfiend

y = -1/4x - 5
So we have a slope of 1/4, meaning for every one unit we go down, we move to the right 4 units. And -5 is the y-intercept, which means the line meets the y axis at -5. Another rough drawing:
|dw:1329864223848:dw|

- shadowfiend

If we put the two together:
|dw:1329864317169:dw|

- shadowfiend

You can see there that they do in fact intersect in quadrant III.

- anonymous

So for A it's Quadrant III?

- shadowfiend

I would assume so. Again, the question isn't *super* clear, but I think that's what it's asking for.

- anonymous

Okay thanks :-)

- shadowfiend

Glad I could help :)

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