Respuesta :

frika

Formula for the sum of n terms of a finite arithmetic series is

[tex]S_n=\dfrac{a_1+a_n}{2}\cdot n.[/tex]

If [tex]n=10,\ a_1=13,\ a_{10}=89,[/tex] then

[tex]S_{10}=\dfrac{13+89}{2}\cdot 10=51\cdot 10=510.[/tex]

Answer: 510.

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