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a fost răspuns

2+7+12+...+177 va roggggg urgentz

Răspuns :

177=2+(n-1)*5
175=5n-5
180=5n
n=36
[tex] S_{36}= \frac{2 a_{1}+(n-1)r }{2}*n [/tex]
[tex] S_{36}= \frac{4+35*5}{2}*36 [/tex]
[tex] S_{36}=(4+175)*18=179*18=3222 [/tex]

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