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a fost răspuns

Calculati: a) 13+14+15+.....+175= ? ; b) 101+102+....+252=? ; c) 108+109+.....+1140=?

Răspuns :

Spidie
a) 13+14+15+.....+175=175*176/2- 12*13/2=15400- 78=15322

b) 101+102+....+252=100+1+100+2+100+3+.....100+52=

=52*100+52*53/2= 5200+1378= 6578

c) 108+109+.....+1140= 1140*1141/2 -107*108/2=650370-5778= 644592