1. Lg²x-lgx-6=0

2. Log5 (3x+1) >2

3. Log2 X - 2Lgx2=-1

Решение: 1) lg (x-1) ²=0; ОДЗ^ x-1> 0 (x-1) ²=1 x²-2x=0 x1=0, посторонний корень x2=2 2) log2 (log3 (x)) = 1 log3 (x) = 2 x=9 3) log3 (log2 (log2 (x)) = 0 log2 (log2 (x)) = 1 log2 (x) = 2 x=4 4) log2 (log3 (x²)) = 2 log3 (x²) = 4 x²=81 x1=9 x2=-9 5) lg x=2 - lg 5 lgx=lg (100/5) x=20