Negative exponential signal's energy and power
An ideal exponential signal $x(t)=e^{at}$ , which extends from $-\infty$ to $\infty$ has infinite energy and infinite power, as for real $a &gt;0$ ( and similarly for real $a &lt; 0$) you have

$$
\mathcal{E}_x = \int_{-\infty}^{\infty} e^{2at} dt = \lim_{t \to \infty} \frac{1}{2a} e^{2a t} \to \infty
$$

and

$$
\mathcal{P}_x = \lim_{T \to \infty} \frac{1}{T} \int_{-T/2}^{T/2} e^{2at} dt = \lim_{T \to \infty} \frac{e^{a T}}{2aT}  \to \infty
$$

Therefore It's neither energy nor power signal. Note that it's not a practical signal and exists only for mathematical purposes.