Partial Fraction Decomposition - Help Please?

knpoe03

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Apr 13, 2020
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Hello!
In my PreCalc class, we are doing a partial fraction decomposition activity. I will link the work that I have so far in the space below. My teacher was absent during the week we learned this unit and instead we had to learn partial fraction decomposition from Youtube videos (which were not very helpful). Anyway, I am unsure if my work so far is correct, as I am unsure if I am doing things the right way.

In the top left corner, my initial addends are listed. Then, we must add and simplify these two addends. From this, we have to perform partial fraction decomposition to show how to get back to the original two addends. I used the Gauss-Jordan Elimination method to find A, B, and C. I'm not sure if this is correct, but I found this technique from awhile back in my math notes and I thought I'd give it a try. I thought I was almost done in getting back to the initial addends, but something just seems off. Can you please let me know where/if I have gone wrong or what I should be doing next?

I'd appreciate your help on this!
 

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  • SUBMISSION PreCalc - Partial Fraction Decomposition Task - Katie Poe (1).pdf
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Please post out your work. Many helpers here will not open an outside link.
 
Since the fractions you started with have integer coefficients, the way to get back to the original is to factor the denominator only over the integers, namely as [MATH](x+2)(x^2+12x-2)[/MATH], and then find coefficients so that [MATH]\frac{-15x^2-341x+60}{(x+2)(x^2+12x-2)} = \frac{A}{x+2}+\frac{Bx+C}{x^2+12x-2}[/MATH]. The radicals make it harder, and overshoot the goal. I did it this way, and the work is not hard at all. But you have an arbitrary choice in combining the 16 with one of the fractions.

If the assignment was to choose your own pair of fractions to start with, you should start with proper fractions, to avoid that difficulty.
 
Since the fractions you started with have integer coefficients, the way to get back to the original is to factor the denominator only over the integers, namely as [MATH](x+2)(x^2+12x-2)[/MATH], and then find coefficients so that [MATH]\frac{-15x^2-341x+60}{(x+2)(x^2+12x-2)} = \frac{A}{x+2}+\frac{Bx+C}{x^2+12x-2}[/MATH]. The radicals make it harder, and overshoot the goal. I did it this way, and the work is not hard at all. But you have an arbitrary choice in combining the 16 with one of the fractions.

If the assignment was to choose your own pair of fractions to start with, you should start with proper fractions, to avoid that difficulty.
Thank you! Unfortunately, the assignment has us plug the dates of our birthday and month in a pre-defined equation. Trust me, if I could change it, I would!!
 
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