Răspunsuri

2014-09-27T11:10:51+03:00
Sn=[(a1+an)/2]*n

a=1+2+3+...+458
n=458
Sn=(1+458)*229=105.111

b=168+169+170+...+192
n=25
Sn=(360/2)*25=180*25=4500

c=15+16+17+...+52
n=38
Sn=(15+52)*19=1273