Proper subset: need example of f : A → B; X, Y⊂A; f(X) \ f(Y ) ⊂f(X \ Y )

[Zuzana]

Proper subset: need example of f : A → B; X, Y⊂A; f(X) \ f(Y ) ⊂f(X \ Y )

Hi!!
i really need an example of this, pleeease
f : A → B; X, Y⊂A;
f(X) \ f(Y ) ⊂f(X \ Y )

 

[stapel]

i really need an example of this, please
f : A → B; X, Y⊂A;
f(X) \ f(Y ) ⊂f(X \ Y )

You have posted this to "Pre-Algebra". Have you not yet studied algebra? If not, I have no idea what you're expected to do with the function notation used here. :shock:

 

[pka]

Hi!!
i really need an example of this, pleeease
f : A → B; X, Y⊂A;
f(X) \ f(Y ) ⊂f(X \ Y )

Suppose that \(\displaystyle A=B=\mathbb{Z}^+\) then \(\displaystyle X\) are the evens and \(\displaystyle Y=\mathbb{Z^+}\setminus X\) and
\(\displaystyle {f(x)=\begin{cases}2^n &\: n\in X\\3^n &\:n\in Y\end{cases}}\)

Can you prove that this function works?