Question

determine o decimo sétimo termo da PA (-6,-1,4...).

Answer 1

razão r = -1 -(-6) = -1 + 6 = 5

an = a1 + (n-1).r
a17 = -6 + 16.5
a17 = 74

Espero ter ajudado.

Answer 2

$PA (-6,-1,4...)\\\\\\a_n=a_{17}=?\\a_1=-6\\ n=17\\ r=-1-(-6)=5\\\\\\ a_n=a_1+(n-1)*r\\\\\\a_{20}=-6+(17-1)*5\to \\\\ a_{20}=-6+16*5\to \\\\ a_{20}=-6+80\to \\\\ a_{20}=74$