Integration by partial fractions problem












-1












$begingroup$


enter image description here



I'm having a lot of trouble with this integral. I don't know what to set A+B equal to. There's an x^4 in the numerator and I'm trying to figure out how to account for it. What am I doing wrong? Thanks.



Problem: $$intfrac{x^4}{4-x^2}space dx$$



What I have tried:



$$frac{x^4}{(2-x)(2+x)}=frac{a}{2-x}+frac{b}{2+x}=frac{a(2+x)+b(2-x)}{(2-x)(2+x)}implies x^4=(a+b)x+2(a+b)$$










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  • 1




    $begingroup$
    First of all, do not present the problem in this way. Instead, learn mathjax and present the problem accordingly. Second of all, in order to use partial fractions it is best to reduce $frac{x^4}{4-x^2}$ to a proper fraction. This means: divide $x^4$ by $4-x^2.$ The quotient will be easy to integrate and you will then apply partial fractions to the remainder. Third of all, if you are still having problems, show significant work in your query, and elaborate on exactly where you are still having problems.
    $endgroup$
    – user2661923
    Jan 17 at 23:39


















-1












$begingroup$


enter image description here



I'm having a lot of trouble with this integral. I don't know what to set A+B equal to. There's an x^4 in the numerator and I'm trying to figure out how to account for it. What am I doing wrong? Thanks.



Problem: $$intfrac{x^4}{4-x^2}space dx$$



What I have tried:



$$frac{x^4}{(2-x)(2+x)}=frac{a}{2-x}+frac{b}{2+x}=frac{a(2+x)+b(2-x)}{(2-x)(2+x)}implies x^4=(a+b)x+2(a+b)$$










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    First of all, do not present the problem in this way. Instead, learn mathjax and present the problem accordingly. Second of all, in order to use partial fractions it is best to reduce $frac{x^4}{4-x^2}$ to a proper fraction. This means: divide $x^4$ by $4-x^2.$ The quotient will be easy to integrate and you will then apply partial fractions to the remainder. Third of all, if you are still having problems, show significant work in your query, and elaborate on exactly where you are still having problems.
    $endgroup$
    – user2661923
    Jan 17 at 23:39
















-1












-1








-1





$begingroup$


enter image description here



I'm having a lot of trouble with this integral. I don't know what to set A+B equal to. There's an x^4 in the numerator and I'm trying to figure out how to account for it. What am I doing wrong? Thanks.



Problem: $$intfrac{x^4}{4-x^2}space dx$$



What I have tried:



$$frac{x^4}{(2-x)(2+x)}=frac{a}{2-x}+frac{b}{2+x}=frac{a(2+x)+b(2-x)}{(2-x)(2+x)}implies x^4=(a+b)x+2(a+b)$$










share|cite|improve this question











$endgroup$




enter image description here



I'm having a lot of trouble with this integral. I don't know what to set A+B equal to. There's an x^4 in the numerator and I'm trying to figure out how to account for it. What am I doing wrong? Thanks.



Problem: $$intfrac{x^4}{4-x^2}space dx$$



What I have tried:



$$frac{x^4}{(2-x)(2+x)}=frac{a}{2-x}+frac{b}{2+x}=frac{a(2+x)+b(2-x)}{(2-x)(2+x)}implies x^4=(a+b)x+2(a+b)$$







integration partial-fractions






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edited Jan 18 at 0:02









coreyman317

774420




774420










asked Jan 17 at 23:06









J.W.J.W.

524




524








  • 1




    $begingroup$
    First of all, do not present the problem in this way. Instead, learn mathjax and present the problem accordingly. Second of all, in order to use partial fractions it is best to reduce $frac{x^4}{4-x^2}$ to a proper fraction. This means: divide $x^4$ by $4-x^2.$ The quotient will be easy to integrate and you will then apply partial fractions to the remainder. Third of all, if you are still having problems, show significant work in your query, and elaborate on exactly where you are still having problems.
    $endgroup$
    – user2661923
    Jan 17 at 23:39
















  • 1




    $begingroup$
    First of all, do not present the problem in this way. Instead, learn mathjax and present the problem accordingly. Second of all, in order to use partial fractions it is best to reduce $frac{x^4}{4-x^2}$ to a proper fraction. This means: divide $x^4$ by $4-x^2.$ The quotient will be easy to integrate and you will then apply partial fractions to the remainder. Third of all, if you are still having problems, show significant work in your query, and elaborate on exactly where you are still having problems.
    $endgroup$
    – user2661923
    Jan 17 at 23:39










1




1




$begingroup$
First of all, do not present the problem in this way. Instead, learn mathjax and present the problem accordingly. Second of all, in order to use partial fractions it is best to reduce $frac{x^4}{4-x^2}$ to a proper fraction. This means: divide $x^4$ by $4-x^2.$ The quotient will be easy to integrate and you will then apply partial fractions to the remainder. Third of all, if you are still having problems, show significant work in your query, and elaborate on exactly where you are still having problems.
$endgroup$
– user2661923
Jan 17 at 23:39






$begingroup$
First of all, do not present the problem in this way. Instead, learn mathjax and present the problem accordingly. Second of all, in order to use partial fractions it is best to reduce $frac{x^4}{4-x^2}$ to a proper fraction. This means: divide $x^4$ by $4-x^2.$ The quotient will be easy to integrate and you will then apply partial fractions to the remainder. Third of all, if you are still having problems, show significant work in your query, and elaborate on exactly where you are still having problems.
$endgroup$
– user2661923
Jan 17 at 23:39












1 Answer
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$begingroup$

When the numerator has higher degree, you should do long division before partial fractions.



$$frac{x^4}{4-x^2} = -x^2 - 4 - frac{16}{x^2-4}.$$
Now you can do partial fractions on the last term.






share|cite|improve this answer









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  • $begingroup$
    Oh wow I knew that. Just escaped me for a second. Thank you.
    $endgroup$
    – J.W.
    Jan 17 at 23:49











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1 Answer
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active

oldest

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1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









3












$begingroup$

When the numerator has higher degree, you should do long division before partial fractions.



$$frac{x^4}{4-x^2} = -x^2 - 4 - frac{16}{x^2-4}.$$
Now you can do partial fractions on the last term.






share|cite|improve this answer









$endgroup$













  • $begingroup$
    Oh wow I knew that. Just escaped me for a second. Thank you.
    $endgroup$
    – J.W.
    Jan 17 at 23:49
















3












$begingroup$

When the numerator has higher degree, you should do long division before partial fractions.



$$frac{x^4}{4-x^2} = -x^2 - 4 - frac{16}{x^2-4}.$$
Now you can do partial fractions on the last term.






share|cite|improve this answer









$endgroup$













  • $begingroup$
    Oh wow I knew that. Just escaped me for a second. Thank you.
    $endgroup$
    – J.W.
    Jan 17 at 23:49














3












3








3





$begingroup$

When the numerator has higher degree, you should do long division before partial fractions.



$$frac{x^4}{4-x^2} = -x^2 - 4 - frac{16}{x^2-4}.$$
Now you can do partial fractions on the last term.






share|cite|improve this answer









$endgroup$



When the numerator has higher degree, you should do long division before partial fractions.



$$frac{x^4}{4-x^2} = -x^2 - 4 - frac{16}{x^2-4}.$$
Now you can do partial fractions on the last term.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Jan 17 at 23:31









angryavianangryavian

41.7k23381




41.7k23381












  • $begingroup$
    Oh wow I knew that. Just escaped me for a second. Thank you.
    $endgroup$
    – J.W.
    Jan 17 at 23:49


















  • $begingroup$
    Oh wow I knew that. Just escaped me for a second. Thank you.
    $endgroup$
    – J.W.
    Jan 17 at 23:49
















$begingroup$
Oh wow I knew that. Just escaped me for a second. Thank you.
$endgroup$
– J.W.
Jan 17 at 23:49




$begingroup$
Oh wow I knew that. Just escaped me for a second. Thank you.
$endgroup$
– J.W.
Jan 17 at 23:49


















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