Question

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

Answer 1

Let $f:A\to B$ be a one-one function.
$\text{Then,}f\left(a\right)\text{can take 5 values,}f\left(b\right)\text{can take 4 values and}f\left(c\right)\text{can take 3 values.}$

Then, the number of one-one functions = 5 $\times$ 4 $\times$ 3 = 60