Math Problem Statement

Five arithmetic means between 6 and -18.

Solution

To find the five arithmetic means between 6 and -18, we need to insert five equally spaced numbers between them. This creates a sequence with seven terms: the first term is 6, the last term is -18, and the five arithmetic means are the intermediate terms.

Step-by-Step Solution:

  1. Identify the Sequence:

    • The sequence is: 6, a2a_2, a3a_3, a4a_4, a5a_5, a6a_6, -18
    • Here, a1=6a_1 = 6 and a7=18a_7 = -18.
  2. Determine the Common Difference dd: The common difference dd can be found using the formula for the nnth term of an arithmetic sequence: an=a1+(n1)×da_n = a_1 + (n-1) \times d For the 7th term (a7a_7): 18=6+(71)×d-18 = 6 + (7-1) \times d 18=6+6d-18 = 6 + 6d 6d=1866d = -18 - 6 6d=246d = -24 d=246=4d = \frac{-24}{6} = -4

  3. Find the Arithmetic Means: Now that we have the common difference d=4d = -4, we can calculate the five arithmetic means: a2=a1+d=64=2a_2 = a_1 + d = 6 - 4 = 2 a3=a2+d=24=2a_3 = a_2 + d = 2 - 4 = -2 a4=a3+d=24=6a_4 = a_3 + d = -2 - 4 = -6 a5=a4+d=64=10a_5 = a_4 + d = -6 - 4 = -10 a6=a5+d=104=14a_6 = a_5 + d = -10 - 4 = -14

Final Answer:

The five arithmetic means between 6 and -18 are 2, -2, -6, -10, -14.

Would you like more details or have any questions?


Here are 5 related questions to further explore the concept:

  1. How would you find the arithmetic means if there were only three means between two numbers?
  2. What is the sum of the sequence 6, 2, -2, -6, -10, -14, -18?
  3. How do you find the common difference if the number of arithmetic means is unknown?
  4. Can you find the geometric means between 6 and -18?
  5. What are the properties of an arithmetic sequence?

Tip: In an arithmetic sequence, the difference between any two consecutive terms is always the same, called the common difference.

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Math Problem Analysis

Mathematical Concepts

Arithmetic Sequences

Formulas

Arithmetic sequence formula: \(a_n = a_1 + (n-1) \times d\)

Theorems

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Suitable Grade Level

Grades 7-9