Final answer:
The signal x(t) has a spectrum that extends theoretically from zero to infinity due to its exponential nature, but in practice, the maximum frequency is limited by the physical constraints of measurement or transmission systems.
Step-by-step explanation:
To determine the maximum frequency in the spectrum of the signal x(t) = 10e-5tu(t), we need to understand the nature of this signal. Here, u(t) represents the unit step function, which makes the signal a one-sided exponential. The maximum frequency is related to how the signal changes in time. For an exponential signal of the form given, the signal itself does not have a traditional sinusoidal frequency component. Therefore, in continuous-time signal analysis, such a signal is considered to have a frequency spectrum that extends from zero to infinity. However, the practical frequency contents vary and would depend on the specific context or system used to analyze or transmit the signal.
Considering x(t) within the context of real-world instruments and systems, the maximum frequency might be bounded by the physical limitations of the devices used for measurement or transmission. Unfortunately, without additional context, determining an exact numerical value for the maximum frequency isn't possible from the given information.