[tex]\bullet \ \text{P.A.} = (-6; 1; 8; ...) \\\\ \bullet a_1 = -6 \\\\ \bullet r = 7, \ \text{pois:} \\ 1 - (-6) = 7 \ \text{ou} \ 8 - 1 = 7 \\\\ \text{Sendo} \ a_n = a_1 + (n - 1) \cdot r: \\\\ \bullet a_{10} = -6 + (10 - 1) \cdot 7 = -6 + 9 \cdot 7 = 57 \\\\ \boxed{a_{10} = 57}[/tex]
