решите уравнение: 5^(3x+1)-5^(3x-3)< =624

Выносим 5^(3x+1) за скобку: 5^(3x+1)*(1-5^(3x-3-3x-1))<=624;
5^(3x+1)*(1-5^(-4))<=624;
5^(3x+1)*(1-1/625)<=624;
5^(3x+1)*(624/625)<=624;
5^(3x+1)<=624/624/625;
5^(3x+1)<=625;
5^(3x+1)<=5^4;
3x+1<=4; 3x<=3; x<=1;
ответ: x<=1;