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a fost răspuns

Calculați sumele:
a) 1+2+3+..+99
b) 2+4+6+...+198
Urgent!!

Răspuns :

Geea

La amandoua folosim suma lui gaus
n(n+1):2
n=ulimul nr

a)
1+2+3+3+...+99

n(n+1):2
99(99+1):2
99*100:2
99*50
4,950

b)
2+4+6+..+198

n(n+1):2
198*(198+1):2
198*199:2
19,701
Alitta
a) 1+2+3+...+99 = (99*100):2=99*50=4950 ;

b)   2+4+6+...+198=2*(1+2+3+...+99)=2*(99*100)/2=9900 ;

Alte intrebari