Question

The number of non-bijective mappings possible from $A=\{1,2,3\}$ to $B=\{4,5\}$ is

• A. $9$
• B. $8$
• C. $12$
• D. $6$

Answer 1

The correct option is B $8$

From $A\to B$ we cannot form any bijective functions because $n\left(a\right)\ne n\left(b\right)$
So, total no of non bijective functions possible = $n(b{)}^{n\left(a\right)}=2^3=8$ (nothing but total no functions possible)