a)
1/946 +2/946 +...+43/946=(1/946)x(1+2+...+43)=
{Aplicam 1+2+...+n=n(n+1)/2, la noi n=43}
=(1/946)x(43x44)/2=(43/946)x(44/2)=(1/22)x22=1
b)
2/255 +4/255 +6/255...+100/255=
(2/255)x(1+2+3+...+50)=(2/255)x(50x51)/2=
(50x51)/255=50x(51/255)=50x(1/5)=10
