Question

Calculați cu factori comuni

Answer 1

Răspuns:

S1=3(1+2+3+...+19)=3(19•20)/2=570

S2=9(1+2+3+...+39)=9(39•40)/2=7020

S3=5(1+2+3+...+400)=5(400•401)/2=401000

S4=4(1+2+3+...+1000)=4(1000•1001)/2=2002000

S5=8(1+2+3+...+100)=8(100•101)/2=40400

S6=11(1+2+3+...+500)=11(500•501)/2=1377750

S7=13(1+2+3+...+20)=13(20•21)/2=2730

S8=20(1+2+3+...+30)=20(30•31)/2=9300