To prove that \( (A \times B) \cup (A \times C) = \{(1,3),(1,4),(1,5),(1,6),(2,3),(2,4),(2,5),(2,6),(3,3),(3,4),(3,5),(3,6)\} \), we will follow these steps:
### Step 1: Define the Sets
We have the following sets:
- \( A = \{1, 2, 3\} \)
- \( B = \{3, 4\} \)
- \( C = \{4, 5, 6\} \)
### Step 2: Calculate \( A \times B \)
The Cartesian product \( A \times B \) consists of all ordered pairs \( (a, b) \) where \( a \in A \) and \( b \in B \).
- For \( a = 1 \):
- \( (1, 3) \)
- \( (1, 4) \)
- For \( a = 2 \):
- \( (2, 3) \)
- \( (2, 4) \)
- For \( a = 3 \):
- \( (3, 3) \)
- \( (3, 4) \)
Thus,
\[
A \times B = \{(1, 3), (1, 4), (2, 3), (2, 4), (3, 3), (3, 4)\}
\]
### Step 3: Calculate \( A \times C \)
Next, we calculate \( A \times C \) which consists of all ordered pairs \( (a, c) \) where \( a \in A \) and \( c \in C \).
- For \( a = 1 \):
- \( (1, 4) \)
- \( (1, 5) \)
- \( (1, 6) \)
- For \( a = 2 \):
- \( (2, 4) \)
- \( (2, 5) \)
- \( (2, 6) \)
- For \( a = 3 \):
- \( (3, 4) \)
- \( (3, 5) \)
- \( (3, 6) \)
Thus,
\[
A \times C = \{(1, 4), (1, 5), (1, 6), (2, 4), (2, 5), (2, 6), (3, 4), (3, 5), (3, 6)\}
\]
### Step 4: Calculate \( (A \times B) \cup (A \times C) \)
Now we take the union of \( A \times B \) and \( A \times C \).
From \( A \times B \):
\[
\{(1, 3), (1, 4), (2, 3), (2, 4), (3, 3), (3, 4)\}
\]
From \( A \times C \):
\[
\{(1, 4), (1, 5), (1, 6), (2, 4), (2, 5), (2, 6), (3, 4), (3, 5), (3, 6)\}
\]
Now, we combine these sets:
- Include \( (1, 3) \)
- Include \( (1, 4) \) (already included)
- Include \( (2, 3) \)
- Include \( (2, 4) \) (already included)
- Include \( (3, 3) \)
- Include \( (3, 4) \) (already included)
- Include \( (1, 5) \)
- Include \( (1, 6) \)
- Include \( (2, 5) \)
- Include \( (2, 6) \)
- Include \( (3, 5) \)
- Include \( (3, 6) \)
Thus, the union is:
\[
(A \times B) \cup (A \times C) = \{(1, 3), (1, 4), (1, 5), (1, 6), (2, 3), (2, 4), (2, 5), (2, 6), (3, 3), (3, 4), (3, 5), (3, 6)\}
\]
### Conclusion
We have shown that:
\[
(A \times B) \cup (A \times C) = \{(1,3),(1,4),(1,5),(1,6),(2,3),(2,4),(2,5),(2,6),(3,3),(3,4),(3,5),(3,6)\}
\]