2 lg5 + lg8 =

Используем свойство логарифмов: n * logₐ b = logₐ (bⁿ) и logₐ b + logₐ c = logₐ (bc).

2 lg5 + lg8 = lg(5²) + lg8 = lg25 + lg8 = lg(25 * 8) = lg200 = lg200