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Hello I have a quick algebra question.

If I have the following expression

$\large \frac{1}{x^2+1}$, and I multiply the numerator and the denominator by $(x^2+1)$.

Is there any way I can get $x^4+x^2−1$?

The reason I am asking this is because on a problem I did this expression came up and it confused I will post the link.

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    This is the question where the expression occurs http://math.stackexchange.com/questions/260117/solving-a-trig-equation-with-inverse2012-12-22
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    Your previous question was closed. This is a literal copy. Why did you think it wouldn't get closed this time?2012-12-22
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    Previous closed question http://math.stackexchange.com/questions/263482/algebra-question-involving-fraction2012-12-22
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    @akkkk Maybe because, now, the question is well-phrased...2012-12-22
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    @DavidMitra: only because of the later edits by Crete and amWhy after my comment, and the question is still not clear to me.2012-12-22
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    In the other question you like you have an equation: $x^2 = \frac{1}{x^2 + 1}$. Clearing the denominator, you have $x^4 + x^2 = 1$ which you just rewrite as $x^4 + x^2 - 1 = 0$...2012-12-22
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    @akkkk If you check the edit history, you'll note that only formatting and grammatical changes were made. The original post was indeed unambiguous.2012-12-22

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