Math Problem Statement

f.

Summation from j equals 1 to 5 left parenthesis 5 j minus 6 right parenthesis∑j=15(5j−6)equals=enter your response here

​(Type an integer or a simplified​ fraction.)

Solution

We are tasked with evaluating the summation:

j=15(5j6)\sum_{j=1}^{5} (5j - 6)

This means we need to calculate the expression 5j65j - 6 for each value of jj from 1 to 5, and then sum the results.

Step 1: Evaluate each term

  • For j=1j = 1: 5(1)6=56=15(1) - 6 = 5 - 6 = -1
  • For j=2j = 2: 5(2)6=106=45(2) - 6 = 10 - 6 = 4
  • For j=3j = 3: 5(3)6=156=95(3) - 6 = 15 - 6 = 9
  • For j=4j = 4: 5(4)6=206=145(4) - 6 = 20 - 6 = 14
  • For j=5j = 5: 5(5)6=256=195(5) - 6 = 25 - 6 = 19

Step 2: Sum the results

Now sum all the evaluated terms:

1+4+9+14+19=45-1 + 4 + 9 + 14 + 19 = 45

Thus, the value of the summation is:

45\boxed{45}

Would you like more details or explanations on any of the steps?


Here are five related questions to extend your understanding:

  1. How do you calculate a summation with a general formula?
  2. What happens if the upper limit of the summation increases to 10?
  3. Can you generalize the formula for summing (5j6)(5j - 6) for any upper limit nn?
  4. How would you compute the sum if the expression inside was quadratic, like 5j265j^2 - 6?
  5. How do arithmetic sequences relate to summations like this?

Tip: Always check each term carefully when performing summations to avoid small arithmetic mistakes!

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Math Problem Analysis

Mathematical Concepts

Summation
Arithmetic Sequences
Basic Algebra

Formulas

Summation formula ∑ (a_j) = a_1 + a_2 + ... + a_n
Arithmetic sequence sum formula S = n/2 * (a_1 + a_n)

Theorems

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Suitable Grade Level

Grades 6-8