Question

Let n(A) = 4 and n(B) = 6, Then the number of one – one functions from 'A' to 'B' is:

Options

• 120

• 360

• 24

• None of these

Answer 1

360

Explanation:

If n(A) = m and n(B) = m ≤ n. Then the number of one – one functions from A to B is –ni/(n – m)!

∴ `(6!)/((6 - 4)!) = (6!)/(2!) = (6 xx 5 xx 4 xx 3 xx 2 xx 1)/(2 xx 1)` = 360