x² − 72x + 36 = 0

Дискриминант: \(D = (-72)^2 - 4 \cdot 1 \cdot 36 = 5184 - 144 = 5040 = 144 \cdot 35\).

\(\sqrt{D} = 12\sqrt{35}\).

Корни: \(x_{1,2} = \frac{72 \pm 12\sqrt{35}}{2} = 36 \pm 6\sqrt{35}\).

Ответ: \(x_1 = 36 - 6\sqrt{35},\ x_2 = 36 + 6\sqrt{35}\).