Math Problem Statement

Consider the statement.

Construct a proof for the statement 'For every integer n, the expression n^2 - n is divisible by 7' by arranging the given sentences in the correct order.

Solution

The image presents a mathematical proof construction task, where the goal is to prove that for any integer nn, the expression n2nn^2 - n is divisible by 7. The proof is constructed by arranging the given statements in the correct logical order.

Let me first transcribe the key parts of the image for clarity and then I’ll help construct the proof:

Given Statements to Arrange:

  1. Subtracting the terms of the equation by factoring n2n=n(n1)n^2 - n = n(n-1).
  2. n(n1)n(n-1) is the product of two consecutive integers.
  3. Both nn and n1n-1 are integers.
  4. By definition, at least one of the integers nn or n1n-1 is divisible by 7.
  5. Dividing both sides of this equation by 7 yields n2n7=n(n1)7\frac{n^2 - n}{7} = \frac{n(n-1)}{7}.
  6. The definition of divisibility requires that n2nn^2 - n is divisible by 7 if and only if n(n1)n(n-1) is divisible by 7.
  7. The sentence n2nn^2 - n is divisible by 7 must be true.

Correct Order to Prove the Statement:

  1. n(n1)n(n-1) is the product of two consecutive integers.
  2. Both nn and n1n-1 are integers.
  3. By definition, at least one of the integers nn or n1n-1 is divisible by 7.
  4. Subtracting the terms of the equation by factoring n2n=n(n1)n^2 - n = n(n-1).
  5. Dividing both sides of this equation by 7 yields n2n7=n(n1)7\frac{n^2 - n}{7} = \frac{n(n-1)}{7}.
  6. The definition of divisibility requires that n2nn^2 - n is divisible by 7 if and only if n(n1)n(n-1) is divisible by 7.
  7. The sentence n2nn^2 - n is divisible by 7 must be true.

This forms the logical progression to prove the statement.


Would you like further explanations or details on any of these steps?
Here are 5 related questions to further enhance understanding:

  1. Why does the product of two consecutive integers guarantee divisibility by 7?
  2. What is the general rule for factoring expressions like n2nn^2 - n?
  3. Can this method of proof be applied to other moduli besides 7?
  4. How does the concept of divisibility tie into factoring in this context?
  5. What are some other examples where such factorization helps in divisibility proofs?

Tip: When working with divisibility problems, factoring is often a useful approach, as it simplifies the structure of the expression into more manageable components.

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Math Problem Analysis

Mathematical Concepts

Number Theory
Divisibility
Algebra

Formulas

n^2 - n = n(n-1)

Theorems

Divisibility Theorem
Properties of Consecutive Integers

Suitable Grade Level

Grades 9-11