Tolong Bantu Cari No 13 Pada Gambar ! Beserta Caranya Ya !

jawab

a = 0,33...
10a = 3,33
10a - a = 3,33 - 0,33
9a = 3
a  = 1/3

b = √{90-√{90 -√{90... →b >0
b² = 90 - √{90-.√{90...
b² = 90 - b
b² + b - 90 = 0
(b +10)(b -9)= 0
b = -10  atau b = 9
b > 0  → b = 9

ᵃlog b = ¹/³log 9 = ³^⁻¹log3²
ᵃlog b = (²/₋₁)  (³log 3)
ᵃlog b = -2