How do you read an expression such as e^{-rt}

Question

I heard people say that the exponential to the power of R times T

e^{rt}

Is it normal?

What about other similar things?

e^{-rt}

Is it read

the exponential to the negative power of R times T

or

the exponential to the power of negative R times T

or

the exponential to the negative exponent of R times T

What do you think about?

Answer 1

The expression e^rt is sloppy. Either write it as $e^{rt}$ or e^{rt} so that you won't confuse it with $e^r\cdot t$. (The expression $\exp(rt)$ is also used very often.)

As long as the context is clear, "$e$ to the power of $rt$" is a usual way to read it.

Similarly, I would write e^{-rt} or $e^{-rt}$ to avoid any confusion. "$e$ to the power of negative $rt$" is reasonable.