13. 5ˣ = 125/6 va 5ʸ = 750 bo‘lsa, x + y ning qiymatini toping.

5ˣ · 5ʸ = (125/6) · 750 = 15625 = 5⁶. Demak, 5⁽ˣ⁺ʸ⁾ = 5⁶.

Javob: x + y = 6.