6. Calculați f(1), ƒ(3) şi ƒ(5), dacă:
a) f: N-Q, f(x) =1/15x;
15
b) f: N->Z, f(x)=-x+2;
c) f: N->Z, ƒ(x)=4-x;
d) f: N->Z, f(x)=|x|+2.
72