Question

sabendo que na PA o terceiro e o setimo termos são respctivamente 2 e 14, determine a razão

Answer 1

Sistema

$a_3=a_1+2r\\ a_7=a_1+6r\\\\ 2=a_1+2r\\ 14=a_1+6r\\\\ -2+14=-a_1+a_1-2r+6r\\\\ 12=4r\\\\ r=\frac{12}{4}\\\\ \boxed{r=3}$