\[x(x - 1) = 72\]
\[x^{2} - x - 72 = 0\]
\[x_{1} + x_{2} = 1;\ \ x_{1} \cdot x_{2} = - 72\]
\[x_{1} = - 8;\ \ x_{2} = 9.\]
\[Ответ:x = - 8;x = 9.\]