lg(x) = t
t²+6-5t = 0
t²-5t+6 = 0
Теорема Виета:
{t1+t2 = 5
{t1•t2 = 6
t1 = 2
t2 = 3
1)lg(x) = 2
x = 10² = 100
2)lg(x) = 3
x = 10³ = 1000
