# If A = {a, b, c} and B = {−2, −1, 0, 1, 2}, write the total number of one-one functions from A to B.

Question:

If A = {abc} and B = {−2, −1, 0, 1, 2}, write the total number of one-one functions from A to B.

Solution:

Let $f: A \rightarrow B$ be a one-one function.

Then, $f(a)$ can take 5 values, $f(b)$ can take 4 values and $f(c)$ can take 3 values.

Then, the number of one-one functions = 5 ×">×× 4 ×">×× 3 = 60