3) 5ˣ²⁻⁶ˣ⁻⁶ = 1;

3) $$ 5^{x^2-6x-6}=1 $$

$$ x^2 - 6x - 6 = 0 $$

$$ D = 36 + 24 = 60 $$

$$ x_1 = \frac{6 + \sqrt{60}}{2} = \frac{6 + 2\sqrt{15}}{2} = 3 + \sqrt{15} $$

$$ x_2 = \frac{6 - \sqrt{60}}{2} = \frac{6 - 2\sqrt{15}}{2} = 3 - \sqrt{15} $$

Ответ: $$3 + \sqrt{15}$$, $$3 - \sqrt{15}$$