To evaluate the limit of the given rational function as \( x \) approaches infinity, we focus on the terms with the highest degree in the numerator and the denominator. The highest degree term in both the numerator and the denominator is \( x^5 \). By dividing every term in the numerator and the denominator by \( x^5 \), we can simplify the expression and find the limit.
Step 1: Identify the Limit
We need to evaluate the limit:
\[
\lim _{x \rightarrow \infty} \frac{4 x^{5}+10 x^{3}+9 x^{2}+2 x+1}{2 x^{5}-3 x^{4}-9 x+5}
\]
Step 2: Simplify the Expression
As \( x \) approaches infinity, the highest degree terms in both the numerator and the denominator dominate the behavior of the function. The highest degree term in the numerator is \( 4x^5 \) and in the denominator is \( 2x^5 \).
Step 3: Divide by the Highest Degree Term
We divide every term in the numerator and the denominator by \( x^5 \):
\[
\frac{4 + \frac{10}{x^2} + \frac{9}{x^3} + \frac{2}{x^4} + \frac{1}{x^5}}{2 - \frac{3}{x} - \frac{9}{x^4} + \frac{5}{x^5}}
\]
Step 4: Evaluate the Limit
As \( x \) approaches infinity, all terms with \( x \) in the denominator approach zero:
\[
\lim _{x \rightarrow \infty} \frac{4 + 0 + 0 + 0 + 0}{2 - 0 - 0 + 0} = \frac{4}{2} = 2
\]
Final Answer
The limit evaluates to \( 2 \), so the answer is \(\boxed{2}\).