I am working through some set theory exercises, and am stuck with this one:
$A = \left \{ 2,4,6,7,11 \right \}$
Find the set S1:
$S1 = \left \{ (n+4): n \in A) \right \}$
Taking away 4 from each member, of the set I get:
$A = \left \{ -2,0,2,3,7 \right \}$
The applet tells me the answer is wrong, but I can't figure out how!