Răspuns:
inlocuiesti x cu -14, -13, -12, -11, ...5, 6, 7
f(-14)= 14+1=15 f(-13)=13+1=14 f(-12)=-(-12)+1 =13 f(-11)=11+1=12
f(0)=1 f(1)=0 f(2)=-2+1=-1 f(3)=-3+1=-2 f(4)=-3 f(5)=-4 f(6)=-5 f(7)=-6
f(-14)+ f(-13) +...+ f(7)= 15+14+...-5-6=
(1+2+3+...+15) - (1+2+3+4+5+6) = folosim suma Gauss
15*16:2- 6*7:2= 15*8 - 3*7= 120-21= 99
