1. R is the relation defined on Z as follows: Vm, n € Z, mRn 5|(m² — n²). (a). Prove that R is an equivalence relation. (b). List all the distinct equivalence classes.

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Discrete Math Please solve a and b

### Equivalence Relations Exercise

**Problem Statement:**

1. **R is the relation** defined on \(\mathbb{Z}\) (the set of all integers) as follows:

   \[\forall m, n \in \mathbb{Z}, \, mRn \iff 5 | (m^2 - n^2).\]

   (a) Prove that \(R\) is an *equivalence relation*.

   (b) List all the distinct *equivalence classes*.

---

**Explanation:**

1. **Defining the Relation:**
   - The relation \(R\) on the set of all integers \(\mathbb{Z}\) relates two integers \(m\) and \(n\) if and only if the difference of their squares, \(m^2 - n^2\), is divisible by 5.
   
2. **Proving Equivalence Relation:**
   - To prove that \(R\) is an equivalence relation, we need to show that \(R\) is reflexive, symmetric, and transitive.

     - **Reflexive:** For all \(m \in \mathbb{Z}\), \(mRm\). This means that \(m^2 - m^2 = 0\) is divisible by 5, which is true since 0 is divisible by any integer.
     
     - **Symmetric:** For all \(m, n \in \mathbb{Z}\), if \(mRn\), then \(nRm\). If \(5 | (m^2 - n^2)\), then \(5 | (n^2 - m^2)\) because \(m^2 - n^2 = -(n^2 - m^2)\). Divisibility is preserved under negation.
     
     - **Transitive:** For all \(m, n, p \in \mathbb{Z}\), if \(mRn\) and \(nRp\), then \(mRp\). If \(5 | (m^2 - n^2)\) and \(5 | (n^2 - p^2)\), then:
       \[
       5 | [(m^2 - n^2) + (n^2 - p^2)] \implies 5 | (m^2 - p^2).
       \]

3. **Listing Equivalence Classes:**
Transcribed Image Text:### Equivalence Relations Exercise **Problem Statement:** 1. **R is the relation** defined on \(\mathbb{Z}\) (the set of all integers) as follows: \[\forall m, n \in \mathbb{Z}, \, mRn \iff 5 | (m^2 - n^2).\] (a) Prove that \(R\) is an *equivalence relation*. (b) List all the distinct *equivalence classes*. --- **Explanation:** 1. **Defining the Relation:** - The relation \(R\) on the set of all integers \(\mathbb{Z}\) relates two integers \(m\) and \(n\) if and only if the difference of their squares, \(m^2 - n^2\), is divisible by 5. 2. **Proving Equivalence Relation:** - To prove that \(R\) is an equivalence relation, we need to show that \(R\) is reflexive, symmetric, and transitive. - **Reflexive:** For all \(m \in \mathbb{Z}\), \(mRm\). This means that \(m^2 - m^2 = 0\) is divisible by 5, which is true since 0 is divisible by any integer. - **Symmetric:** For all \(m, n \in \mathbb{Z}\), if \(mRn\), then \(nRm\). If \(5 | (m^2 - n^2)\), then \(5 | (n^2 - m^2)\) because \(m^2 - n^2 = -(n^2 - m^2)\). Divisibility is preserved under negation. - **Transitive:** For all \(m, n, p \in \mathbb{Z}\), if \(mRn\) and \(nRp\), then \(mRp\). If \(5 | (m^2 - n^2)\) and \(5 | (n^2 - p^2)\), then: \[ 5 | [(m^2 - n^2) + (n^2 - p^2)] \implies 5 | (m^2 - p^2). \] 3. **Listing Equivalence Classes:**
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