Question

Calculati suma : f(1)+f(2)+f(3)+.....+f(50) ,iar f(×)=-×+3

Answer 1

$f(1)+f(2)+f(3)+...+f(50)=(-1+3)+(-2+3)+(-3+3)+... \\ +(-50+3)=3*50-1-2-3-...-50=150-(1+2+3+...+ \\ 50)=150- \frac{50*51}{2}=150-25*51=150- 1275=-1125.$