Math Problem Statement

ok now this. "the first term in a sequence is 15. The common ration is -3. Write the first 5 terms of the sequence." and make the answer writable on a paper

Solution

Sure! This problem describes a geometric sequence, where each term is found by multiplying the previous term by the common ratio.

Given:

  • First term a1=15a_1 = 15
  • Common ratio r=3r = -3

The formula for the nth term of a geometric sequence is: an=a1rn1a_n = a_1 \cdot r^{n-1}

Now, let’s find the first five terms:

  1. First term a1=15a_1 = 15
  2. Second term a2=15×(3)=45a_2 = 15 \times (-3) = -45
  3. Third term a3=45×(3)=135a_3 = -45 \times (-3) = 135
  4. Fourth term a4=135×(3)=405a_4 = 135 \times (-3) = -405
  5. Fifth term a5=405×(3)=1215a_5 = -405 \times (-3) = 1215

The first five terms are:

15,45,135,405,121515, -45, 135, -405, 1215

If you want to write it neatly on paper, you could lay it out like this:

a1=15,a2=45,a3=135,a4=405,a5=1215a_1 = 15, \quad a_2 = -45, \quad a_3 = 135, \quad a_4 = -405, \quad a_5 = 1215


Would you like a more detailed explanation or clarification? Also, here are some related questions for further practice:

  1. How do you calculate the nth term of a geometric sequence?
  2. What happens if the common ratio is a fraction or a decimal?
  3. How can you identify the terms in a geometric sequence if only the common ratio and a few terms are given?
  4. How would you write the general formula for a geometric sequence?
  5. How do geometric sequences relate to exponential functions?

Tip: Always double-check your multiplication when working with negative common ratios to ensure you don't make sign errors!

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Math Problem Analysis

Mathematical Concepts

Geometric Sequence
Sequences and Series
Exponents

Formulas

nth term formula for geometric sequence: a_n = a_1 * r^(n-1)

Theorems

Geometric Sequence Formula

Suitable Grade Level

Grades 7-9