Question

Let a function f:A → B, where A = {1, 2, 3} and B = {6, 7, 8} such that a < b ⇒ f(a) < f(b), where a ∈ A & b ∈ B. Then find the number of one-one function between A to B.

Answer 1

is 3 since 

(i) 1 < 2 ⇒ f(1) = 6 < f(2) = 7 

(ii) 1 < 3 ⇒ f(1) = 6 < f(3) = 8 

(iii) 2 < 3 ⇒ f(2) = 7 < f(3) = 8