Question

Seja a PA(1,5,25,31,25),calcule o valor da soma de seus termos

Answer 1

Resposta:

Soma = 65

Explicação passo-a-passo:

$S_{n}=\dfrac{(a_{1}+a_{n})\cdot\;n}{2}\\[0,1cm]S_{5}=\dfrac{(1+ 25)\cdot\;5}{2}\\[0,1cm]S_{5}=\dfrac{26\cdot\;5}{2}\\[0,1cm]S_{5}=\dfrac{130}{2}\\[0,1cm]S_{5}=\boxed{65}$