9. Let [tex]\lim_{n \rightarrow \infty} a_n = 3[/tex], [tex]\lim_{n \rightarrow \infty} b_n = -3[/tex], and [tex]\lim_{n \rightarrow \infty} c_n = \frac{1}{3}[/tex].

What is the value of [tex]\lim_{n \rightarrow \infty} \frac{2a_n + b_n}{c_n}[/tex]?

(A) 0
(B) 1
(C) 3
(D) 9



Answer :

To solve the problem, we need to determine [tex]\(\lim_{n \to \infty} \frac{2a_n + b_n}{c_n}\)[/tex], given the limits of the sequences [tex]\(a_n\)[/tex], [tex]\(b_n\)[/tex], and [tex]\(c_n\)[/tex] as [tex]\(n\)[/tex] approaches infinity.

Given:
[tex]\[ \lim_{n \to \infty} a_n = 3, \lim_{n \to \infty} b_n = -3, \text{and} \lim_{n \to \infty} c_n = \frac{1}{3} \][/tex]

Step-by-step breakdown:

1. Evaluate the limit of the numerator:
[tex]\[ \lim_{n \to \infty} (2a_n + b_n) \][/tex]
According to the given limits:
[tex]\[ \lim_{n \to \infty} (2a_n + b_n) = 2 \cdot \lim_{n \to \infty} a_n + \lim_{n \to \infty} b_n \][/tex]
Substituting the given limits:
[tex]\[ = 2 \cdot 3 + (-3) = 6 - 3 = 3 \][/tex]

2. Evaluate the limit of the denominator:
[tex]\[ \lim_{n \to \infty} c_n = \frac{1}{3} \][/tex]

3. Combine the results to find the limit of the ratio:
[tex]\[ \lim_{n \to \infty} \frac{2a_n + b_n}{c_n} = \frac{\lim_{n \to \infty} (2a_n + b_n)}{\lim_{n \to \infty} c_n} \][/tex]
Substituting the calculated limits:
[tex]\[ = \frac{3}{\frac{1}{3}} = 3 \cdot 3 = 9 \][/tex]

Hence, the value of [tex]\(\lim_{n \to \infty} \frac{2a_n + b_n}{c_n}\)[/tex] is [tex]\(9\)[/tex].

So the correct answer is:
[tex]\[ \boxed{9} \][/tex]