Small math problem

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Zanghfei
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Small math problem

Post by Zanghfei » Wed Jun 12, 2013 8:12 am

So I have Math MELS in Friday.
So IF I have.

1. General Form
0 = 5x + y + 5

2. To, Function Form
-y = 5x + 5

(Correct me If I'm wrong.)

3. My Math resolution is
-y / -y = 5x / -1 + 5 / -1

4. My conclusion
y = -5x - 5

Do I do wrong?
(Derp, I know this isn't a Math Forum.)

WaeV
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Re: Small math problem

Post by WaeV » Wed Jun 12, 2013 10:22 am

It would be much more straightforward to go from this:

0 = 5x + y + 5

Leave y positive and subtract the other terms:

Code: Select all

     0     =  5x + y + 5
-(5x + 5)     -(5x + 5)
To get function form but with y positive:

-5x - 5 = y

aka

y = -5x - 5
Last edited by WaeV on Fri Jun 14, 2013 6:49 am, edited 1 time in total.
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Zanghfei
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Re: Small math problem

Post by Zanghfei » Wed Jun 12, 2013 12:08 pm

Zanghfei wrote: 2. To, Function Form
-y = 5x + 5

4. My conclusion
y = -5x - 5

I am quite unsure and unconvinced that this really the right answer.

Sparky
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Re: Small math problem

Post by Sparky » Fri Jun 14, 2013 4:53 am

If you're looking for positive values, do what you are doing but if you have a negative value, multiply by -1 on both sides:

0 = 5x + y + 5

subtract y on both sides

-y = 5x + 5

negative value to positive value by multiplying both sides by -1:

y = -5x - 5

You can also do the same process with x, but simplifying also:

0 = 5x + y + 5

subtract 5x from both sides

-5x = y + 5

multiply by -1

5x = -y - 5

simplify by dividing by 5

x = (-y/5) - 1
Either you are groping for answers, or you are asking God and listening to Jesus.

Zanghfei
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Re: Small math problem

Post by Zanghfei » Thu Jul 18, 2013 1:46 pm

Thank Sparky!
But it is to late and I got 69% and it doesn't make sense

002
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Re: Small math problem

Post by 002 » Thu Jul 18, 2013 3:07 pm

well, if everyone wants to do it.

Here's how I would "solve" it.

0 = 5x + y + 5

y = -(5x + 5) ~ subtract non-y terms

y = -5(x + 1) ~ Factor out 5.

or, to get your answer, you can instead

0 = 5x + y + 5

y = -(5x + 5) ~ subtract non-y terms

y = -5x - 5 ~ Multiply by -1 coefficient


You can use either answer for graphing, as both are probably correct. A factored equation is easier to graph, though.

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