MHT CET2018MathematicsSets and Relations
If X = 4 n - 3 n - 1 : n ∈ N and Y = 9 n - 1 : n ∈ N , then X ∩ Y =
Options
- AX
- BY
- Cϕ
- D0
Correct answer
A. X
Step-by-step solution
X = 4 n − 3 n − 1 : n ∈ N X = ( 1 + 3 ) n − 3 n − 1 : n ∈ N X = 1 + 3 n + 3 2 n ( n − 1 ) 2 ! + 3 3 n ( n − 1 ) ( 2 n − 1 ) 6 ....3 n − 1 X = 3 2 ( n − 1 ) n ( 1 2 ! + 3 ( 2 n − 1 ) 6 + ..... ) X = 9 ( n − 1 ) n ( 1 2 ! + ...... ) Y = 9 ( n − 1 ) : n ∈ N ∴ X ⊆ Y ∴ X ∩ Y = X (or) Put n = 1 , 2 , 3 , 4 , 5 , 6 , ..... in X and Y X = 0 , 9 , 54 , .... Y = 0 , 9 , 18 , 27 , 36 , 45 , 54 , 63...... X ⊆ Y ∴ X ∩ Y = X