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If A × B ⊆ C × D and A × B ≠ ϕ, prove that A ⊆ C and B ⊆ D. |
Answer» Given: A × B ⊆ C × D and A × B ≠ ϕ Need to prove: A ⊆ C and B ⊆ D Let us consider, (x, y) (A × B)......... (1) ⇒ (x, y)∈(C × D) [as A × B ⊆ C × D] .......... (2) From (1) we can say that, x∈ A and y∈B .......... (a) From (2) we can say that, x∈C and y∈D ....... (b) Comparing (a) and (b) we can say that, ⇒ x∈A and x∈C ⇒ A ⊆ C Again, ⇒ y∈B and y∈D ⇒ B ⊆ D [Proved] |
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