Prove that A intersection (B minus C) is equal to (A intersection B) m...
Proof of A ∩ (B - C) = (A ∩ B) - (A ∩ C)
Step 1: Definition of A ∩ (B - C)
- A ∩ (B - C) represents the elements that are common in set A and the elements of set B that are not in set C.
Step 2: Definition of (A ∩ B) - (A ∩ C)
- (A ∩ B) - (A ∩ C) represents the elements that are common in both set A and set B, but not in set A and set C simultaneously.
Step 3: Showing Equality
- Let x be an arbitrary element in A ∩ (B - C).
- This means x ∈ A and x ∈ B but x ∉ C.
- So, x ∈ A and x ∈ B, which implies x ∈ A ∩ B.
- Also, x ∉ C, which means x ∉ A ∩ C.
- Therefore, x ∈ (A ∩ B) - (A ∩ C), proving A ∩ (B - C) ⊆ (A ∩ B) - (A ∩ C).
Step 4: Reverse Inclusion
- Let y be an arbitrary element in (A ∩ B) - (A ∩ C).
- This means y ∈ A, y ∈ B, but y ∉ C.
- So, y ∈ A and y ∈ B, which implies y ∈ A ∩ (B - C).
- Also, y ∉ C, which means y ∉ A ∩ C.
- Therefore, y ∈ A ∩ (B - C), proving (A ∩ B) - (A ∩ C) ⊆ A ∩ (B - C).
Step 5: Conclusion
- From steps 3 and 4, we have shown that A ∩ (B - C) ⊆ (A ∩ B) - (A ∩ C) and (A ∩ B) - (A ∩ C) ⊆ A ∩ (B - C).
- Hence, A ∩ (B - C) = (A ∩ B) - (A ∩ C) is proved.
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