In (7x+2) = in (5x-20)

log5^2x-log5x=0

log3 (3x-1) >3

Используй определение логарифма:

loga (x) = b; x=a^b.

1) x=762=49.

2) x = (2/3) ^3=8/27.

3) x=5^ (-3) = 1/5^3=1/125.

4) x = (4/7) ^ (-2) = (7/4) ^2 = 49/16.

5) x+2=2.5; x=0,5.

6) x=10^ (-2) = 1/100.

7) x=1.

8) x^3+1=1/0,5; x^3+1=2; x^3=1; x=1.