log4(5x-1)-log4x <= log4 5

log4((5x-1)/(4x)) <= log4 5

(5x-1)/(4x) <= 5

5x-1 <= 5*4x

5x-1 <= 20x

20x-5x >= -1

15x >= -1

x >= -1/15

Решим данное неравенство: log4(5x-1)-log4x<=log4 5

5х-1/х<=5

5х-1<=5x

-1<=0

1) 5x-1>0

5x>1

x>1/5

2) x>0

Ответ. Неравенство верно при x>1/5.