Вопрос:

Ответ:

\[(a - 7)x = a² - 14a + 49\]

\[x = \frac{(a - 7)^{2}}{a - 7} = a - 7\]

\[1.\ a = 7 \Longrightarrow x - любое.\]

\[2.\ a \neq 7 \Longrightarrow x = a - 7.\]