Question

Fie multimea A={-3,-2,-1,0,1,2,3}  si o functie bijectiva f : A cu valori in A. Sa se calculeze suma: f(-3)+ f(-2)+ f(-1)+ f(0)+ f(1)+ f(2)+ f(3).

Answer 1

Deoarece f bijectiva deducem ca valorile functiei $f(x)\in\{-3,-2,-1,0,1,2,3\}$
f(-3)+ f(-2)+ f(-1)+ f(0)+ f(1)+ f(2)+ f(3)=(-3)+(-2)+(-1)+0+1+2+3( nu obligatoriu in aceasta ordine)=0