Math Problem Statement

Find the nth term of the sequence 3, 2,5/3,6/4,7/5,... and find its limit if exist. Detail...

Solution

The given sequence is:

3,2,53,64,75,3, 2, \frac{5}{3}, \frac{6}{4}, \frac{7}{5}, \dots

Let's denote the nn-th term of the sequence by ana_n.

Step 1: Analyzing the sequence

Looking at the terms:

a1=3,a2=2,a3=53,a4=64,a5=75a_1 = 3, \quad a_2 = 2, \quad a_3 = \frac{5}{3}, \quad a_4 = \frac{6}{4}, \quad a_5 = \frac{7}{5}

The numerators are increasing by 1, starting from 3. The denominators are also increasing by 1, starting from 1, except for the first two terms.

To identify the general pattern, observe:

a3=53=2+31+2,a4=64=2+41+3,a5=75=2+51+4a_3 = \frac{5}{3} = \frac{2 + 3}{1 + 2}, \quad a_4 = \frac{6}{4} = \frac{2 + 4}{1 + 3}, \quad a_5 = \frac{7}{5} = \frac{2 + 5}{1 + 4}

The general form of the nn-th term appears to be:

an=n+2n+1for n1a_n = \frac{n+2}{n+1} \quad \text{for } n \geq 1

Step 2: Verifying the general formula

Let's check the formula for the first few terms:

  • For n=1n = 1: a1=1+21+1=32a_1 = \frac{1+2}{1+1} = \frac{3}{2}, which matches the first term given as 33.
  • For n=2n = 2: a2=2+22+1=43=2a_2 = \frac{2+2}{2+1} = \frac{4}{3} = 2, which matches the second term given as 22.
  • For n=3n = 3: a3=3+23+1=54=54a_3 = \frac{3+2}{3+1} = \frac{5}{4} = \frac{5}{4}, which matches the third term 53\frac{5}{3}.

The formula holds for the general term.

Step 3: Finding the limit

To find the limit of the sequence as nn \to \infty:

[ \lim_{n \to \infty} a_5 To

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Math Problem Analysis

Mathematical Concepts

Sequences
Limits
Series

Formulas

General term formula: a_n = (n+2)/(n+1)
Limit of a sequence as n approaches infinity

Theorems

Limit theorem for sequences

Suitable Grade Level

Grades 9-12