Question

Calculati urmatoarele sume:1.s1=1+2+3+....+34 2.s2=8+9+10+.....+35 3.s3=11+12+13+.......+60
4.s4=10+20+30+.......+350
5.s5=11+22+33+......+121
6.s6=7+13+19+........+103
7.s7=2+6+10+.........+102​

Answer 1

s1= 1+2+3+...+342

1•(1+2+3+...+342)=?

1•342•(342+1):2=?

1•342•342:2

342•342:2=

116964:2= 58482

s3=11+12+13+...+60

11•(1+2+3+...+20)

11•20•(20+1):2

11•20•21:2

220•21:2

4620:2= 2310

s4=10+20+30+...+350

10•(1+2+3+...+35)

10•35•(35+1):2

10•35•36:2

350•18=6300

s5= 11+22+33+...+121

11•(1+2+3+...+11)

11•11•(11+1):2

11•11•12:2

121•6= 726

Sunt la inceput cu aceste calcule, așa că sper că îți este de folos 4 ex