y=log₄(4ˣ⁻¹−16)

4ˣ⁻¹−16 > 0;

4ˣ⁻¹ > 16;

4ˣ⁻¹ > 4²;

x - 1 > 2;

x > 2 + 1

x > 3

D(y) = (3; ∞).