Always exponential growth when multiplication factor is greater than 1

Question

Let an exponential function take the form
$$y=a \cdot b^x$$ I know if a is greater than $0$ and b is greater than $1$, this is called exponential growth.

What if a is less than $0$ and b is greater than $1$? Is this still exponential growth?

Answer 1

When $b<1$, this is known as “exponential decay” and is a common term as it is used to model many systems. The case $a<0$ is less commonly used and doesn’t have a generally agreed upon name, I’ve heard it called exponentially decreasing though.