If you answer this question please give a full and valid pro

If you answer this question please give a full and valid proof. State what you know, what you are proving, and conclude why your proof works. Thank you.

Reminder w NU Let A be a set with m elements and let B be a set with n elements, where min C w and m n. Suppose f i an function from A to B. Show that f is s not an injection.

Solution

Assume f were an injection

So no two elements in A map to the same element in B

So, |f(A)|=|A|<=|B|

ie n<=m

which is a contradiction

Hence, f is not an injection