Question

Let $A=\{1,2,3\}$ . Which of the following functions on A is invertible?

• A. $f=\left\{\right(1,1),(2,1),(3,1\left)\right\}$
• B. $f=\left\{\right(1,2),(2,3),(3,1\left)\right\}$
• C. $f=\left\{\right(1,2),(2,3),(3,2\left)\right\}$
• D. $f=\left\{\right(1,1),(2,2),(3,1\left)\right\}$

Answer 1

The correct option is A $f=\left\{\right(1,1),(2,1),(3,1\left)\right\}$

$A=\{1,2,3\}$

$\therefore$ $A$ is invertible when obviously

$f=\{(1,1),(2,1),(3,1)\}$