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Rebecarebeca12345
a fost răspuns

S=17+20+23+26+...+464

Răspuns :

aflăm cate nr sunt:(464-17):3+1=447:3+1=149+1=150
s=(464+17)*150:2=481*75=36075
[tex]17=14+3[/tex]
[tex]20=14+6=14+3*2[/tex]
[tex]23=14+9=14+3*3[/tex]
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[tex]464=14+150=14+3*150[/tex]
Daca adunam toate numerele

[tex]S=17+20+23+..+464=14+3*1+14+3*2+14+3*3+...+14+3*150=14*150+3(1+2+3+..+n)=14*150+3*\frac{150*151}{2}=2100+33975=36075[/tex]

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