Lg в квадрате(x-1)-2*lg(x-1)=15

lg²(x-1) - 2*lg(x-1)=15

одз x > 1

lg(x - 1) = y

y² - 2y - 15 = 0

D = b² - 4ac = 4 + 60 = 64

y₁₂ = (2 +- 8)/2 = 5   -3

y₁ = -3  

lg(x₁ - 1) = -3

x₁ - 1 = 10^(-3)

x₁ = 1.001

y₂ = 5

lg(x₂ - 1) = 5

x₂ - 1 = 10^5

x₂ = 100001