Which of the following functions represent exponential decay?

y = 2x

y = - 2x

y = 1/2^x

7 = 2^0.5x

I'm going to assume to meant to type a y instead of the 7 in the last function, since that's the only one that would be expontential decay.

It is decay because the exponent is less than one. (the. 5x)

All the other options have an exponent of 1.