Image of a function

Let $m_f: $m_RR $m_rightarrow $m_RR be a $val16 function, and let A be a $val11 subset of $m_RR. Consider the image B=$m_f(A) and the inverse image C=$m_f-1(A) of A.

What can be said about B and C?

You must choose the most precise replies.


Bounder and union

Let A and B be two subsets of $m_RR. Suppose that A (resp. B) is $val7 by a (resp. by b). Are the following two statements true?

I. A $m_cap B is $val7 by $val13.

II. A $m_cup B is $val7 by $val13.