Răspunsuri

2014-10-06T15:39:12+03:00
A) 51 , b)60 , c) 70.
Calculezi prima cu ultima , a doua cu penultima si tot asa :) .

  • Utilizator Brainly
2014-10-06T15:48:30+03:00
A) n(n+1):2 => Suma lui Gauss 
    1+2+3+4+......+50 =50(50+1):2=1275

b) 55(55+1):2-(1+2+3+4)=
     55(55+1):2-4(4+1):2=
     1540-10=1530

c) 60(60+1):2-(1+2+3+4+5+6+7+8+9)=
    60(60+1):2-9(9+1):2=
    1830-45=1785