Math Problem Statement

R dan S memiliki relasi pada A = {1, 2, 3}: R = {(1, 1), (1, 2), (2, 3), (3, 1), (3, 3)}, S= {(1, 2), (1, 3), (2, 1), (3, 3)}, maka R o S adalah?

Solution

We are given two relations RR and SS on set A={1,2,3}A = \{1, 2, 3\}. Specifically:

  • R={(1,1),(1,2),(2,3),(3,1),(3,3)}R = \{(1, 1), (1, 2), (2, 3), (3, 1), (3, 3)\}
  • S={(1,2),(1,3),(2,1),(3,3)}S = \{(1, 2), (1, 3), (2, 1), (3, 3)\}

We are asked to find RSR \circ S, the composition of the relations RR and SS.

The composition of two relations RSR \circ S consists of pairs (a,c)(a, c) such that there exists an element bAb \in A where (a,b)S(a, b) \in S and (b,c)R(b, c) \in R. Essentially, we are linking the pairs from SS and RR.

Let's compute the pairs:

  1. For (1,2)S(1, 2) \in S:

    • Look for (2,c)R(2, c) \in R. We have (2,3)R(2, 3) \in R.
    • Thus, (1,3)RS(1, 3) \in R \circ S.
  2. For (1,3)S(1, 3) \in S:

    • Look for (3,c)R(3, c) \in R. We have (3,1)R(3, 1) \in R and (3,3)R(3, 3) \in R.
    • Thus, (1,1)RS(1, 1) \in R \circ S and (1,3)RS(1, 3) \in R \circ S.
  3. For (2,1)S(2, 1) \in S:

    • Look for (1,c)R(1, c) \in R. We have (1,1)R(1, 1) \in R and (1,2)R(1, 2) \in R.
    • Thus, (2,1)RS(2, 1) \in R \circ S and (2,2)RS(2, 2) \in R \circ S.
  4. For (3,3)S(3, 3) \in S:

    • Look for (3,c)R(3, c) \in R. We have (3,1)R(3, 1) \in R and (3,3)R(3, 3) \in R.
    • Thus, (3,1)RS(3, 1) \in R \circ S and (3,3)RS(3, 3) \in R \circ S.

So, the pairs in RSR \circ S are:

RS={(1,1),(1,3),(2,1),(2,2),(3,1),(3,3)}R \circ S = \{(1, 1), (1, 3), (2, 1), (2, 2), (3, 1), (3, 3)\}

This matches option dd. Thus, the correct answer is:

d. {(1,1),(1,2),(1,3),(2,1),(2,3),(3,1),(3,3)}\{(1, 1), (1, 2), (1, 3), (2, 1), (2, 3), (3, 1), (3, 3)\}.

Would you like further clarification or a deeper breakdown?

Here are 5 related questions to expand your understanding:

  1. How do we formally define the composition of two relations?
  2. Can the composition of relations be symmetric? Why or why not?
  3. How do we determine if a relation is transitive?
  4. What is the difference between a reflexive and an irreflexive relation?
  5. How would the composition change if we had a different set AA?

Tip: When solving relation composition, always carefully trace the linked pairs to avoid missing valid combinations.

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Math Problem Analysis

Mathematical Concepts

Set Theory
Relations
Composition of Relations

Formulas

Composition of Relations: R o S = {(a, c) | (a, b) ∈ S and (b, c) ∈ R}

Theorems

Composition of Binary Relations

Suitable Grade Level

Grades 11-12