f (x) = Log[a,a^x - 1] (a > 0 且a ≠ 1) 求x为何值 函数值大于1
当a > 1 时,a^x - 1 > a,
a^x > a + 1,
x > Log[a,a + 1],
当0 < a < 1 时,0 < a^x - 1 < a,
1 < a^x < a + 1,
Log[a,a + 1] < x < 0,