Partial Fraction: Solving x^3+1/x^2+4

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SUMMARY

The discussion focuses on solving the expression (x^3 + 1) / (x^2 + 4) using long division and partial fraction decomposition. After performing long division, the result is x - (4x - 1) / (x^2 + 4). The user encounters difficulty in further simplifying the expression -4x - 1 / (x^2 + 4) into the form bx + c / (x^2 + 4). A suggestion is made to split the fraction into two parts: -4x / (x^2 + 4) and -1 / (x^2 + 4), with the latter potentially involving a trigonometric substitution related to arctan(x).

PREREQUISITES
  • Understanding of polynomial long division
  • Familiarity with partial fraction decomposition
  • Knowledge of trigonometric substitutions
  • Basic calculus concepts, particularly integration techniques
NEXT STEPS
  • Practice polynomial long division with various rational functions
  • Study partial fraction decomposition techniques for different types of denominators
  • Learn about trigonometric substitutions, specifically for integrals involving quadratic expressions
  • Explore integration techniques related to arctan(x) and other inverse trigonometric functions
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Students studying calculus, particularly those focusing on integration techniques and partial fraction decomposition, as well as educators looking to enhance their teaching methods in these areas.

tnutty
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Homework Statement


x^3+1 / x^2+4


Homework Equations




The Attempt at a Solution



after using long division i get : x + -(4x-1) / (x^2+4)

then using partial fraction :

-4x-1 / x^2+4 = bx+c / x^2+4

then i am stuck because if what i have
is correct then they both are the same and in the same form.
 
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tnutty said:
-4x-1 / x^2+4 = bx+c / x^2+4

then i am stuck because if what i have
is correct then they both are the same and in the same form.

-\frac{4x-1}{x^2+4}=\frac{1}{x^2+4}-\frac{4x}{x^2+4}...:wink:
 
Once you gotten to (-4x-1)/(x^2+4) you probably want to leave the partial fractions trail. Split it into -4x/(x^2+4) and -1/(x^2+4). The first one is a simple substitution. I'm going to guess the second one might be something related to arctan(x)? Try a trig substitution.
 

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