Найдите формулу n–го члена арифметической прогрессии: 18, 14, 10, 6, ….

\[18,\ 14,\ 10,\ 6,\ldots\ \ \]

\[a_{1} = 18;\ \ a_{2} = 14:\]

\[d = 14 - 18 = - 4.\]

\[a_{n} = a_{1} + d(n - 1) =\]

\[= 18 - 4 \cdot (n - 1) =\]

\[= 18 - 4n + 4 = 22 - 4n\]

\[a_{n} = 22 - 4n.\ \]