Limit of a Rational Fraction of Polynomials as x Tends to Infinity

If a function  
\[f(x)\]
  is given as a rational fraction of two polynomials,  
\[P(x), \; Q(x)\]
  so that  
\[f(x)= \frac{P(x)}{Q(x)}\]
  then we can evaluate the limit as  
\[x \rightarrow \infty\]
  as in the following example.
\[\begin{equation} \begin{aligned} lim_{x \rightarrow \infty} \frac{x^2-2x+3}{4x^2-x-1} &= lim_{x \rightarrow \infty} \frac{1-2/x+3/x^2}{4-1/x-1/x^2} \\ &= lim_{x \rightarrow \infty} \frac{1-0+0}{4-0-0} \\ &- \frac{1}{4} \end{aligned} \end{equation}\]

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