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NTA Abhyas JEE Main2020MathematicsSets and RelationsPractice

If the difference between the number of subsets of two sets A and B is 120 , then n A × B is equal to

Options

  1. A21
  2. B25
  3. C18
  4. D24

Correct answer

A. 21

Step-by-step solution

Let, n A = α   &   n B = β Given, 2 α - 2 β = 120 ⇒ α , β ≡ 7,3 , 3,7 ∴ n ( A × B ) = 7 × 3 = 21

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