Math Problem Statement

Find the 93rd term of the arithmetic sequence -5, -15, -25, ...

Solution

To find the 93rd term of an arithmetic sequence, we can use the formula for the nn-th term of an arithmetic sequence:

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

where:

  • a1a_1 is the first term of the sequence,
  • dd is the common difference, and
  • nn is the term number we want to find.

Step-by-Step Solution

  1. Identify the first term (a1a_1):

    • The first term, a1a_1, is given as 5-5.
  2. Determine the common difference (dd):

    • The difference between consecutive terms is 15(5)=10-15 - (-5) = -10.
    • So, d=10d = -10.
  3. Plug the values into the formula:

    • We need to find the 93rd term, so n=93n = 93.

a93=5+(931)(10)a_{93} = -5 + (93 - 1) \cdot (-10)

  1. Simplify the expression:
    • 931=9293 - 1 = 92
    • 92(10)=92092 \cdot (-10) = -920
    • a93=5+(920)a_{93} = -5 + (-920)
    • a93=925a_{93} = -925

Answer

The 93rd term of the sequence is 925-925.

Would you like more details on any part of this solution?


Here are some related questions to expand your understanding:

  1. What is the formula for the sum of the first nn terms of an arithmetic sequence?
  2. How would you find the common difference if only given two non-consecutive terms?
  3. Can an arithmetic sequence have a positive common difference and still produce negative terms?
  4. How can we determine if a sequence is arithmetic by looking at a few terms?
  5. What changes in the formula if we start counting terms from a different point?

Tip: Always verify the common difference by checking a few terms to ensure consistency.

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Math Problem Analysis

Mathematical Concepts

Arithmetic Sequences
Algebra

Formulas

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

Theorems

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Suitable Grade Level

Grades 8-10