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Mathematics 21 Online
OpenStudy (anonymous):

Please help by explaining this to me? :)

OpenStudy (anonymous):

OpenStudy (anonymous):

the denominator cannot be zero so \(x+5\neq 0\) meaning \(x\neq -5\)

OpenStudy (anonymous):

Okay, you're referring to these types of expressions? Not just this specific problem, right? How would you solve this problem?

zepdrix (zepdrix):

Haper that is how you solve for the restrictions on x. It looks like the rest of your question got cut off, `and what` is all i see in the picture.

OpenStudy (anonymous):

those value(s) represent.***

OpenStudy (anonymous):

My teachers tend to want things done step by step and for me to explain as much as possible but I don't know how to "properly" solve this problem. I solved all the others but none of them, I had to explain :\

zepdrix (zepdrix):

Soooo I would start by multiplying through by the LCD, which in this case appears to be 6(x+5).

zepdrix (zepdrix):

And that will give us thisssss, \[\Large 6(x+3)+x(x+5)=5(x+5)\] I skipped a bit of the simplification there, so lemme know if that was confusing.

OpenStudy (anonymous):

I'm still confused :\

zepdrix (zepdrix):

\[\Large \frac{x+3}{x+5}+\frac{x}{6}=\frac{5}{6}\]Let's try multiplying by each denominator one at a time, maybe that will make more sense to you :o So let's start by multiplying both sides by 6.\[\Large 6\left(\frac{x+3}{x+5}+\frac{x}{6}\right)=\left(\frac{5}{6}\right)6\]

zepdrix (zepdrix):

On the left, we distribute the 6 to each term in the brackets,\[\Large \frac{6(x+3)}{x+5}+\frac{6x}{6}=\frac{5\cdot6}{6}\]

zepdrix (zepdrix):

So then we get some nice cancellations,\[\Large \frac{6(x+3)}{x+5}+\frac{\cancel6x}{\cancel6}=\frac{5\cdot\cancel6}{\cancel6}\]

zepdrix (zepdrix):

\[\Large \frac{6(x+3)}{x+5}+x=5\]So that cleaned things up a bit for us, right? :o

OpenStudy (anonymous):

Very much :D

zepdrix (zepdrix):

So we still have another denominator to deal with :O Repeat this process with x+5.

zepdrix (zepdrix):

\[\Large (x+5)\left(\frac{6(x+3)}{x+5}+x\right)=\left(5\right)(x+5)\]

zepdrix (zepdrix):

\[\Large \frac{6(x+5)(x+3)}{x+5}+x(x+5)=5(x+5)\]

zepdrix (zepdrix):

and then cancel some stuff :o

OpenStudy (anonymous):

You cancel out the x + 5 so 6(x + 3) + x(x + 5) = 5(x + 5)... and thats it?

OpenStudy (anonymous):

Do you multiply the numbers?

zepdrix (zepdrix):

Yah we have to multiply out some stuff from there.

zepdrix (zepdrix):

\[\Large 6(x+3)+x(x+5)=5x+25\]What do you get on the left side? :)

OpenStudy (anonymous):

6x + 18 + 2x + 5x

OpenStudy (anonymous):

So 13x + 18? Please tell this is correct and that I'm not going crazy here

zepdrix (zepdrix):

Woops! x*x is not 2x! :O

OpenStudy (anonymous):

It's x^2? I keep getting that confused apparently because I thought it was x^2 but someone told me it was 2x -.-

zepdrix (zepdrix):

\[\Large 2x=x+x\qquad\qquad\qquad x^2=x\cdot x\] Yah there is a difference :D heh

zepdrix (zepdrix):

Hmm the rest of it looks good though :o \[\Large 6x + 18 + x^2 + 5x=5x+25\]

OpenStudy (anonymous):

Can you please continue, mon? I think I'm getting it but I want to see if I'm correct since I have two theories :)

zepdrix (zepdrix):

Subtracting 5x from each side, and rearranging some stuff, gives us,\[\Large x^2+6x+18=25\]

zepdrix (zepdrix):

Subtracting 25 from each side,\[\Large x^2+6x-7=0\]

zepdrix (zepdrix):

From here we can either use the Quadratic Formula or factor the polynomial if possible.

zepdrix (zepdrix):

Looks like it factors in this case. Do you see the factors? :)

OpenStudy (anonymous):

7, -1 :)

zepdrix (zepdrix):

\[\Large (x+7)(x-1)=0\]Yah that sounds right.

zepdrix (zepdrix):

Understand how to solve for x from here? :o

OpenStudy (anonymous):

Yes! :)

OpenStudy (anonymous):

you can also solve it by transposing x/6 to R.H.S \[\frac{ x+3 }{x+5 }=\frac{ 5 }{ 6 }-\frac{ x }{ 6 }=\frac{ 5-x }{6 }\] cross multiply \[6x+18=-\left( x-5 \right)\left( x+5 \right)=-\left( x ^{2}-25 \right)\] \[x ^{2}-25+6x+18=0,or x ^{2}+6x-7=0\] further you have the solutions as given by friends.

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