`đkxđ:` 7 - x $\neq$ 0 ⇔ x $\neq$ 7
`(x - 7)/36 = -4/(7 - x)`
⇔ `(x - 7)/36 = 4/(x - 7)`
⇔ `(x - 7)² = 36 . 4`
⇔ `(x - 7)² = 144`
⇔ \(\left[ \begin{array}{l}x - 7 = 12\\x - 7 = -12\end{array} \right.\)
⇔ \(\left[ \begin{array}{l}x = 19\\x = -5\end{array} \right.\)
`Vậy x = { 19 ; -5 }`
