Вопрос:

Ответ:

\[a_{1} = 0,5;\ \ a_{23} = - 2,3\]

\[a_{23} = a_{1} + 22d\]

\[- 2,3 = 0,5 + 22d\]

\[22d = - 2,8\]

\[d = - \frac{28}{220}\]

\[d = - \frac{7}{55}.\]