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Mathematics 18 Online
OpenStudy (anonymous):

Need to know how to solve a rational equation

OpenStudy (anonymous):

The following equation is one that I made up so I can solve the problem I have to do on my own.

OpenStudy (anonymous):

|dw:1407178562891:dw| this is the equation I made

OpenStudy (anonymous):

|dw:1407178841444:dw|

OpenStudy (anonymous):

I don't know why it came out like that

OpenStudy (agreene):

I would start like this: \[(x^3-8x)^{-1}=\frac{x}x+\frac8x-6\]

OpenStudy (anonymous):

okay hold on let me put the other equation in that form @agreene

OpenStudy (anonymous):

Where did the ^-1 outside the first parenthesis come from? @agreene

OpenStudy (agreene):

its shorthand for the division

OpenStudy (agreene):

\[\frac1x=x^{-1}\]

OpenStudy (anonymous):

so the ^-1 is coming from the 1 in the first part of the equation?

OpenStudy (agreene):

yes

OpenStudy (anonymous):

okay so I put my equation in that form whats next?

OpenStudy (anonymous):

you there? @agreene

OpenStudy (anonymous):

what do I doo next?

OpenStudy (agreene):

lol im trying to remember.. im a bit rusty on the algebra here

OpenStudy (anonymous):

haha its okay

OpenStudy (agreene):

\[\frac1{x^3-8x}=1+\frac8x-6\] \[\frac1{x^3-8x}=\frac8x-5\] \[\frac1{x^3-8x}-\frac8x=-5\]

OpenStudy (aum):

The least common denominator is (x^3-8x). Multiply throughout by (x^3-8x). You will get a fourth degree polynomial which cannot be easily solved unless you use a graphic calculator. Note that x cannot be 0 or \(\pm\sqrt{8}\) because that would make the denominator zero.

OpenStudy (anonymous):

My equation was

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