Math Problem Statement

Compute the sums: 1. Σ(2i - 1) from i = 1 to 3, 2. Σ(k^3 + 2) from k = -1 to 1.

Solution

Let's compute the sums based on the given images.

Problem 1:

We are asked to compute the sum:

i=13(2i1)\sum_{i=1}^{3} (2i - 1)

This means we need to evaluate the expression 2i12i - 1 for each integer ii from 1 to 3, and then sum the results:

  1. For i=1i = 1: 2(1)1=21=12(1) - 1 = 2 - 1 = 1
  2. For i=2i = 2: 2(2)1=41=32(2) - 1 = 4 - 1 = 3
  3. For i=3i = 3: 2(3)1=61=52(3) - 1 = 6 - 1 = 5

Now, sum these results:

1+3+5=91 + 3 + 5 = 9

Thus, the value of the sum is 9.


Problem 2:

The sum to compute is:

k=11(k3+2)\sum_{k=-1}^{1} (k^3 + 2)

This means we need to evaluate k3+2k^3 + 2 for k=1,0,1k = -1, 0, 1 and sum the results:

  1. For k=1k = -1: (1)3+2=1+2=1(-1)^3 + 2 = -1 + 2 = 1
  2. For k=0k = 0: 03+2=0+2=20^3 + 2 = 0 + 2 = 2
  3. For k=1k = 1: 13+2=1+2=31^3 + 2 = 1 + 2 = 3

Now, sum these results:

1+2+3=61 + 2 + 3 = 6

Thus, the value of the sum is 6.


Would you like further details or have any questions?

Here are five related questions you could explore:

  1. How would the sum change in Problem 1 if the upper limit was 4 instead of 3?
  2. What is the general formula for the sum of an arithmetic series like in Problem 1?
  3. In Problem 2, how does changing the lower or upper limit of the summation affect the result?
  4. What happens to the sum in Problem 2 if you change the expression to k2+2k^2 + 2?
  5. How can sigma notation be used to represent other types of series, such as geometric series?

Tip: When working with sigma notation, always make sure to evaluate each term individually before summing, as small mistakes in one term can affect the entire result!

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Math Problem Analysis

Mathematical Concepts

Summation
Algebra

Formulas

Summation formula: Σ (expression)
Cubic and linear arithmetic expressions

Theorems

Summation properties
Basic polynomial evaluations

Suitable Grade Level

Grades 8-10