To find the oblique asymptote of a rational function, the book I'm reading says to divide the denominator of a fraction into the numerator. The example rational function it gives is $$\frac{x^2 - 9} {x + 2}.$$ The result of the long division it says to perform is $x - 2$. However when I divide $\frac{x^2 - 9} {x +2}$ I get $x - 5$. Is the answer in the book $x - 2$ incorrect, or am I performing the long division incorrectly by getting $x - 5$ as the quotient?
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1$-5$ is the remainder. You can check using that the remainder of the division of $p(x)$ by $x+2$ is $p(-2)$. – Bernard Aug 19 '15 at 20:29
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1You could use $x^2-9=(x^2-4)-5$ to see that $x-2$ is the correct quotient. – user84413 Aug 19 '15 at 20:31