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question on partial fraction decomposition

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after breaking down this fraction [math]\frac{x^2+2}{x^3-x}[/math]

I got [math]\frac{-2}{x} + \frac{3}{2(x-1)} + \frac{1}{2(x+1)}[/math]

but using my ti-89 and mathematic there is an extra +1 at the end so I was wondering where does the +1 come from?

mathematic and ti-89 gave [math]\frac{-2}{x}+\frac{3}{2(x-1)}+\frac{1}{2(x+1)}+1[/math]

after breaking down this fraction (x^2+2)/(x^3-x)

I got (-2)/(x)+3/(2(x-1))+1/(2(x+1))

but using my ti-89 and mathematic there is an extra +1 at the end so I was wondering where does the +1 come from?

mathematic and ti-89 gave (-2)/(x)+3/(2(x-1))+1/(2(x+1))+1

 

Try to use LaTex where possible' date=' makes things easier to read :)

 

after breaking down this fraction [math]\frac{x^2+2}{x^3-x}[/math]

I got [math]\frac{-2}{x} + \frac{3}{2(x-1)} + \frac{1}{2(x+1)}[/math]

but using my ti-89 and mathematic there is an extra +1 at the end so I was wondering where does the +1 come from?

mathematic and ti-89 gave [math]\frac{-2}{x} + \frac{3}{2(x-1)} + \frac{1}{2(x+1)} + 1[/math]

 

 

... is that what you meant?

 

Cheers,

 

Ryan Jones

yep, thanks, I have no clue how to use LaTex. I am noob...

 

I understand :)

 

If you need help you can try looking at the examples here and you can ask the questions there too and I'm shure someone will be glad to help you :)

 

Cheers,

 

Ryan Jones

so I was wondering where does the +1 come from?

 

It comes from you entering the expression into your calculator wrong. You put [imath]x^3+2[/imath] in for the numerator.

  • Author

woops, I typed it wrong here I meant [math]\frac{x^3+2}{x^3-x}[/math] so why is there extra +1 for mathematica and calculator? when I do it I get [math] \frac{A}{X} + \frac{B}{X-1} + \frac{C}{X+1}[/math] that is how I got my 3 terms.

If you do a long division first it is obvious

[math]

\frac{(x^3-x)+(x +2)}{x^3-x} = 1 + \frac{x+2}{x^3-x}

[/math]

  • Author

thank you, I didn't see how the numerator is bigger than the denominator, so when the largest power is same on top and bottom, long division is neccesary? This one looked like a proper fraction to me :(

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