[tex]a_1=-9\\\\a_2=a_1-8\to a_2=-9-8=-17\\\\a_3=a_2-8\to a_3=-17-8=-25\\\\a_4=a_3-8\to a_4=-25-8=-33\\\\\text{The general term of an arithmetic sequence:}\\\\a_n=a_1+(n-1)d\\\\a_1-first\ term\\d-common\ difference\\\\\text{We have}\ a_1=-9\ \text{and}\ d=-8.\ \text{Substitute:}\\\\a_n=-9+(n-1)(-8)=-9-8n+8=-8n-1\\\\\text{Put n = 43 and calculate}\ a_{43}\\\\a_{43}=-8(43)-1=-344-1=-345\\\\Answer:\ \boxed{?=-345}[/tex]
