Math Problem Statement

Given the recursive formula for the geometric sequence a₁ = 5, aₙ = (2/5)aₙ₋₁, find the second term of the sequence.

Solution

To find the second term a2a_2 of the geometric sequence, we use the given recursive formula:

an=25an1a_n = \frac{2}{5} a_{n-1}

where the first term a1=5a_1 = 5.

Step-by-Step Solution:

  1. Substitute n=2n = 2 in the recursive formula to find a2a_2: a2=25a1a_2 = \frac{2}{5} a_1

  2. Substitute a1=5a_1 = 5: a2=25×5a_2 = \frac{2}{5} \times 5

  3. Simplify the expression: a2=2a_2 = 2

Answer:

The correct answer is: a2=2a_2 = 2

Would you like further details or have any questions?


Here are five related questions for further practice:

  1. What is the third term a3a_3 in this sequence?
  2. What is the general formula for the nn-th term in this geometric sequence?
  3. If the common ratio were 35\frac{3}{5} instead of 25\frac{2}{5}, what would a2a_2 be?
  4. How would the sequence change if a1a_1 were a different value, say 10?
  5. How can you determine if a sequence is geometric or arithmetic by looking at its terms?

Tip: In a geometric sequence with a recursive formula, multiply each term by the common ratio to find the next term.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Geometric Sequences
Recursive Formulas

Formulas

aₙ = r * aₙ₋₁

Theorems

Properties of Geometric Sequences

Suitable Grade Level

Grades 8-10