\[\boxed{\text{541.}\text{\ }\text{ОК\ ГДЗ\ -\ домашка\ на\ 5}}\]
\[\textbf{а)}\ a_{n} = - 10 + 2n\]
\[a_{1} = - 10 + 2 = - 8;\]
\[a_{2} = - 10 + 4 = - 6;\]
\[d = 2.\]
\[\textbf{б)}\ a_{n} = 8 - 3n\]
\[a_{1} = 8 - 3 = 5;\]
\[a_{2} = 8 - 6 = 2.\]
\[d = - 3.\]