Sorry, there was a mistake. The first one was originally a linear function. I thought it was an exponential function. Well, since it is increasing, 3-A > 0, then A < 3. In addition, when X > 7, we can get that when A > 1, the function is monotonically increasing, and when x=7, there must be a ≥ 60. ), and then take the intersection, 9/4 ≤ A < 3.