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Mathematics 28 Online
OpenStudy (anonymous):

Solve the linear equation.

OpenStudy (anonymous):

\[\frac{ x-6 }{ -3 } + \frac{ x+9 }{ 9 } = x + 4\]

OpenStudy (anonymous):

assuming for x?

OpenStudy (anonymous):

I don't remember whether to actually divide -6-3 or subtract them... or maybe it's -6+9 what do you mean o.o

OpenStudy (anonymous):

you said solve the linear equation, then you posted one, I am assuming you mean to solve for x

OpenStudy (anonymous):

I think so...

OpenStudy (anonymous):

okay how much information do you need? Do you know how to do any of it, or need all of it?

OpenStudy (anonymous):

I think I just need to know how to start it off. Anytime I see fractions, my mind blanks e.e

OpenStudy (anonymous):

okay, what you need to do is find a common denominator on the left side

OpenStudy (anonymous):

like this

OpenStudy (anonymous):

\[-3((x-6)/-3) =(-3x+18)/9\]

OpenStudy (anonymous):

Then combine the numerators to get -3+18+x+9 which is -2x +27 all over 9

OpenStudy (anonymous):

Then multiply both sides by 9 to get rid of the denominator

OpenStudy (anonymous):

would you like me to keep going?

OpenStudy (anonymous):

I'm a little confused...

OpenStudy (anonymous):

\[-3(\frac{ x-6 }{ -3 })= \frac{ -3x+18 }{ 9 }\]

OpenStudy (anonymous):

That is the first step, does that make sense?

OpenStudy (anonymous):

\[\frac{ -3+18 }{ 9 }+ \frac{ x+9 }{ 9 }\] \[\frac{ -3x+18+x+9 }{ 9 }= \frac{ -3x+x+18+9 }{ 9}= \frac{ -2x+27 }{ 9 }\]

OpenStudy (anonymous):

does this make more sense?

OpenStudy (anonymous):

what happened to the x+4 on the right side and how -3x+4 get to the right of the equal sign? I understand how you did the second problem but for some reason I'm not understanding the same steps in the original problem >.<

OpenStudy (anonymous):

the steps I just did are from the problem you gave. I was only working with the left side, I can do that because all I did was multiply by 1 and rewrote it. I don't know where you got -3x+4.

OpenStudy (anonymous):

o.o I meant x+4 that was on the RHS and that second problem was the next step from the actual problem that you just did? e.e oh my goodness so sorry I'm a little slow lol

OpenStudy (anonymous):

So do you understand what I was doing? I can reexplain it if you want?

OpenStudy (anonymous):

I understand every step except for how you knew how to get the second step (where you place the -3 in a distributive position)

OpenStudy (anonymous):

I know you needed a common denominator but I mean...like...where does that 3 even come from

OpenStudy (anonymous):

That should be \[\frac{ -3 }{ -3 }\] I meant to do that. The reason I knew to use the -3 is because -3 is a factor of 9 so I wanted to get 9 as my common denominator, so since -3 *-3 is 9 i multiplied -3 by the top and bottom of the first fraction on the LHS. Does that make sense?

OpenStudy (anonymous):

so if the equation looked like \[\frac{ x-4 }{ -2 } + \frac{ x-8 }{ 4 } = x - 6\] and you needed a common denominator, you'd \[-2(\frac{ x -4 }{ -2 }) +\frac{ x-8 }{ 4 } = x-6\]

OpenStudy (anonymous):

or no...?

OpenStudy (anonymous):

yes, except it should be \[\frac{ -2 }{ -2 }\] so you are multiplying by 1 and not changing the problem but rather changing the appearance. That was a notation mistake on my part.

OpenStudy (anonymous):

oooh I think I get it now

OpenStudy (anonymous):

Would you like for me to keep going?

OpenStudy (anonymous):

Yes please, if you don't mind.

OpenStudy (anonymous):

Not at all, I live for this, literally I am a math teacher.

OpenStudy (anonymous):

Lol, glad to hear and I appreciate your time and effort. Thank you.

OpenStudy (anonymous):

So now you multiply both sides by 9 to get rid of the denominators. \[9(\frac{ -2x+27 }{ 9 })=9(x+4)\] the 9s on the LHS will cancel out so you will be left with \[-2x+27=9(x+4)\]

OpenStudy (anonymous):

Your welcome

OpenStudy (anonymous):

Would you like for me to continue?

OpenStudy (anonymous):

Yes please

OpenStudy (anonymous):

now you distribute to get, \[-2x+27=9x+36\]

OpenStudy (anonymous):

Then you get to pick one of the terms, any of them. Which one do you want to use?

OpenStudy (anonymous):

o.o um... 9x?

OpenStudy (anonymous):

okay so now you move 9x by subtracting it since it is positive, by the way, this will work with any term you choose. \[-2x-9x+27=36\]

OpenStudy (anonymous):

Now you add like terms: \[-11x+27=36\]

OpenStudy (anonymous):

Then you move the +27 since you need to get the variable by itself\[-11x+27-27=36-27\] \[-11x=9\]

OpenStudy (anonymous):

Then divide both sides by -11 and you will get our answer

OpenStudy (anonymous):

so basically \[x = -\frac{ 9 }{ 11 }\]

OpenStudy (anonymous):

Should be

OpenStudy (anonymous):

Thank you very much c:

OpenStudy (anonymous):

Your very welcome

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