Răspunsuri

Cel mai inteligent răspuns!
2014-10-04T11:01:37+03:00
1+2.+3....+9=9x10:2=45
1+2+3+..+399=399x400:2=79800
101+102+...+199=100(1+2+3+...++99)=100x99x100:2=495000
1+3+5+...+499=249²=62001
2014-10-04T11:08:03+03:00
1+2+........+199=               n=(199 -1) :(2-1) +1         n=198 :1+1        n=198+1    n=199        S=[(199+1) ori 199] :2=            S= (200 ori 199):2=39 800 :2=19 900
sper ca ai exemplu din clasa,formula
cu placere,sunt usoare