Math Problem Statement

An arithmetic sequence begins: -4, -1, 2, 5, ... What is the nth term rule for the sequence?

Solution

The sequence provided is an arithmetic sequence: 4,1,2,5,-4, -1, 2, 5, \dots

Step 1: Identify the common difference

In an arithmetic sequence, the common difference (dd) is constant between consecutive terms.

d=1(4)=3d = -1 - (-4) = 3 d=2(1)=3d = 2 - (-1) = 3 d=52=3d = 5 - 2 = 3

Thus, the common difference d=3d = 3.

Step 2: Find the first term

The first term of the sequence is a1=4a_1 = -4.

Step 3: Use the formula for the nnth term of an arithmetic sequence

The formula for the nnth term (ana_n) of an arithmetic sequence is:

an=a1+(n1)da_n = a_1 + (n - 1)d

Substitute a1=4a_1 = -4 and d=3d = 3:

an=4+(n1)3a_n = -4 + (n - 1) \cdot 3 an=4+3n3a_n = -4 + 3n - 3 an=3n7a_n = 3n - 7

Conclusion:

The nnth term rule for the sequence is:

an=3n7a_n = 3n - 7

Would you like more details or have any questions? Here are some related questions to explore:

  1. How do you find the sum of the first nn terms in an arithmetic sequence?
  2. What happens to the sequence if the common difference changes?
  3. How can you determine the number of terms in a finite arithmetic sequence?
  4. How does the arithmetic sequence differ from a geometric sequence?
  5. Can you derive the nth term formula for a sequence given any two terms?

Tip: Always verify the common difference in each step to ensure the sequence remains arithmetic.

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Math Problem Analysis

Mathematical Concepts

Algebra
Arithmetic Sequences

Formulas

nth term of an arithmetic sequence: a_n = a_1 + (n - 1)d

Theorems

Arithmetic sequence nth term formula

Suitable Grade Level

Grades 7-9