Question

Calcule a soma dos 50 primeiros termos da P.A. de razão 4 e primeiro termo -12. *

2 pontos

a) 4000

b) 4200

c) 4300

d) 4350

e) 4450​

Answer 1

Resposta:

$\red{ \boxed{ \boxed{ \boxed{ c)4300}}}}$

Explicação passo-a-passo:

primeiro temos que descobrir o valor de a50.

$</strong><strong>a_</strong><strong>{n} = a1 + (n - 1) \times r \\ </strong><strong>a_</strong><strong>{50} = - 12 + (50 - 1) \times 4 \\ </strong><strong>a_</strong><strong>{50} = - 12 + 49 \times 4 \\ </strong><strong>a_</strong><strong>{50} = - 12 + 196 \\</strong><strong>a</strong><strong>_</strong><strong>{50 } = 184$

agora iremos calcular a soma dos 50 termos da P.A

$</strong><strong>s_</strong><strong>{n} = \frac{(</strong><strong>a_</strong><strong>{1} + </strong><strong>a_</strong><strong>{n}) \times n}{2} \\ </strong><strong>s_</strong><strong>{50} = \frac{( - 12 + 184) \times 50}{2} \\ </strong><strong>s_</strong><strong>{50} = \frac{172 \times 50}{2} \\ </strong><strong>s_</strong><strong>{50} = \frac{8600}{2} \\ \red{ \boxed{ \boxed{ \boxed{</strong><strong>s_</strong><strong>{50} = 4300}}}}</strong><strong>$

espero ter ajudado :)