Math Problem Statement

Evaluate the arithmetic series: ∑(n=1 to 10) (-2 + (4/3)n)

Solution

The problem asks to evaluate the following arithmetic series:

n=110(2+43n)\sum_{n=1}^{10} \left( -2 + \frac{4}{3}n \right)

This represents the sum of terms from n=1n = 1 to n=10n = 10 of the sequence defined by the expression 2+43n-2 + \frac{4}{3}n.

Steps for solution:

  1. Recognize the Arithmetic Series Format: The series is in the form: an=2+43na_n = -2 + \frac{4}{3}n where the first term (a1a_1) is when n=1n=1 and the last term (a10a_{10}) is when n=10n=10.

  2. Find the First and Last Terms:

    • First term (a1a_1) when n=1n=1: a1=2+43(1)=2+43=63+43=23a_1 = -2 + \frac{4}{3}(1) = -2 + \frac{4}{3} = -\frac{6}{3} + \frac{4}{3} = -\frac{2}{3}
    • Last term (a10a_{10}) when n=10n=10: a10=2+43(10)=2+403=63+403=343a_{10} = -2 + \frac{4}{3}(10) = -2 + \frac{40}{3} = -\frac{6}{3} + \frac{40}{3} = \frac{34}{3}
  3. Use the Arithmetic Series Sum Formula: The sum SnS_n of an arithmetic series is given by: Sn=n2(a1+an)S_n = \frac{n}{2} \left(a_1 + a_n\right) where nn is the number of terms. In this case, n=10n = 10, a1=23a_1 = -\frac{2}{3}, and a10=343a_{10} = \frac{34}{3}.

  4. Calculate the Sum: S10=102(23+343)S_{10} = \frac{10}{2} \left(-\frac{2}{3} + \frac{34}{3}\right) Simplifying inside the parentheses: 23+343=323-\frac{2}{3} + \frac{34}{3} = \frac{32}{3} Now, compute the sum: S10=5×323=1603S_{10} = 5 \times \frac{32}{3} = \frac{160}{3}

Final Answer:

The sum of the series is 1603\frac{160}{3}.

Would you like further details or any other questions answered?

Here are some related questions to explore:

  1. How would the sum change if we increased the number of terms?
  2. What is the general formula for the nn-th term of an arithmetic sequence?
  3. How do you derive the formula for the sum of an arithmetic series?
  4. What would happen if the common difference in the series were negative?
  5. How do you calculate the sum of an infinite arithmetic series?

Tip: When dealing with arithmetic series, always confirm the first term, common difference, and last term to simplify calculations.

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Math Problem Analysis

Mathematical Concepts

Arithmetic Series
Summation
Sequences

Formulas

Sum of an arithmetic series: S_n = (n/2) * (a_1 + a_n)
General term of an arithmetic sequence: a_n = a + (n-1)d

Theorems

Arithmetic Series Sum Formula

Suitable Grade Level

Grades 9-11