15. 11ˣ = 11/4 va 11ʸ = 484 bo‘lsa, x + y ning qiymatini toping.

11ˣ · 11ʸ = (11/4) · 484 = 1331 = 11³. Demak, 11⁽ˣ⁺ʸ⁾ = 11³.

Javob: x + y = 3.