Math Problem Statement

If A = {5, 6, 7}, B = {7, 8}, and C = {5, 8}, then find (i) (A × B) ∩ (A × C) and (ii) A × (B ∩ C).

Solution

The given problem involves sets and their Cartesian products and intersections. Let me break it down.

Problem

Given sets:

  • A={5,6,7}A = \{5, 6, 7\},
  • B={7,8}B = \{7, 8\},
  • C={5,8}C = \{5, 8\},

We are tasked to find:

  1. (A×B)(A×C)(A \times B) \cap (A \times C),
  2. A×(BC)A \times (B \cap C).

Step-by-Step Solution:

(i) (A×B)(A×C)(A \times B) \cap (A \times C)

  1. Find A×BA \times B: A×B={(a,b)aA,bB}A \times B = \{(a, b) \mid a \in A, b \in B\} Using the sets, A×BA \times B becomes: A×B={(5,7),(5,8),(6,7),(6,8),(7,7),(7,8)}.A \times B = \{(5, 7), (5, 8), (6, 7), (6, 8), (7, 7), (7, 8)\}.

  2. Find A×CA \times C: A×C={(a,c)aA,cC}A \times C = \{(a, c) \mid a \in A, c \in C\} Using the sets, A×CA \times C becomes: A×C={(5,5),(5,8),(6,5),(6,8),(7,5),(7,8)}.A \times C = \{(5, 5), (5, 8), (6, 5), (6, 8), (7, 5), (7, 8)\}.

  3. Intersection (A×B)(A×C)(A \times B) \cap (A \times C): Common elements between A×BA \times B and A×CA \times C: (A×B)(A×C)={(5,8),(6,8),(7,8)}.(A \times B) \cap (A \times C) = \{(5, 8), (6, 8), (7, 8)\}.


(ii) A×(BC)A \times (B \cap C)

  1. Find BCB \cap C: Intersection of BB and CC: BC={8}.B \cap C = \{8\}.

  2. Cartesian product A×(BC)A \times (B \cap C): Using A={5,6,7}A = \{5, 6, 7\} and BC={8}B \cap C = \{8\}, we get: A×(BC)={(5,8),(6,8),(7,8)}.A \times (B \cap C) = \{(5, 8), (6, 8), (7, 8)\}.


Final Results:

  1. (A×B)(A×C)={(5,8),(6,8),(7,8)}(A \times B) \cap (A \times C) = \{(5, 8), (6, 8), (7, 8)\},
  2. A×(BC)={(5,8),(6,8),(7,8)}A \times (B \cap C) = \{(5, 8), (6, 8), (7, 8)\}.

Would you like further explanation or examples? Here are five related questions to consider:

  1. What are the key differences between a Cartesian product and an intersection of sets?
  2. How would the results change if the sets BB and CC were disjoint?
  3. Can you generalize the result for (A×B)(A×C)(A \times B) \cap (A \times C) for any sets A,B,CA, B, C?
  4. How can these operations be visualized in a Venn diagram or grid representation?
  5. What is the significance of the elements common between BB and CC in these calculations?

Tip: Cartesian products grow quickly in size as the sets increase; understanding their structure is crucial for simplifying problems like these!

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Math Problem Analysis

Mathematical Concepts

Set theory
Cartesian products
Set intersections

Formulas

A × B = {(a, b) | a ∈ A and b ∈ B}
(A × B) ∩ (A × C) = Common elements of A × B and A × C
A × (B ∩ C) = {(a, b) | a ∈ A and b ∈ (B ∩ C)}

Theorems

Set theory properties
Cartesian product operations

Suitable Grade Level

Grades 8-10