Решите задачу:
3^(x+1)+3^(x-1)<28<br>9*3^(x-1)+3^(x-1)<28<br>(9+1)*3^(x-1)<28<br>3^(x-1)<28/10<br>3^(x-1)<14/5<br>x-1 < log(3, 14/5) x < 1 + log(3, 14/5) x < log(3, 42/5)