Question

calcule a soma dos 30 primeiros termos de uma P.A. (4,10,...)

Answer 1

$r=10-4\\ \boxed{r=6}\\\\ A_n=A_1+(n-1).r\\ A_{30}=4+29.6\\ A_{30}=174+4\\ \boxed{A_{30}=178}\\\\ S_n=\frac{(A_1+A_n).n}2\\ S_{30}=\frac{(4+178).30}2\\ S_{30}=182.15\\ \boxed{S_{30}=2730}$