4. 5ᵃ = 625 va 3ᵇ = 1/9 bo‘lsa, a + b ning qiymatini toping.

625 = 5⁴, demak a = 4. 1/9 = 3⁻², demak b = −2.

Javob: a + b = 4 + (−2) = 2.