Question

01 Calcule a soma dos 30 primeiros termos da P.A. (2,7, 12, 17, ...).
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Answer 1

fórmulas:

an=a1(n-1)r

Sn=(a1+an)•n/2

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a30=2+(30-1)5

a30=2+29•5

a30=2+145=147

Sn=(2+147)•30/2

Sn=149•30/2

Sn=4470/2

Sn=2235