Let A = {1, 2, 3, 4, 5, 6}. The number of one-one functions f : A A such that , and f(2) + f(3) = 5, is ________. [2026]
(72)
A = {1, 2, 3, 4, 5, 6}
f : A A
Case I : (f(2), f(3)) = (4, 1) or (1, 4), then Choices of values of f(1) {3, 5, 6} = 3
Number of ways 2 x 3 x 6 = 36
Case II : (f(2), f(3) = (2, 3) or (3, 2), then Choices of values f(1) {4, 5, 6} = 3
Number of ways = 2 x 3 x 6 = 36
Total number of functions = 36 + 36 = 72.