# y=-5^x, find domain and range?

$x \in \mathbb{R} , f \left(x\right) < 0$
We know that $y = {a}^{x}$ can take any value for $x$, so the domain is $x \in \mathbb{R}$.
However, $y = - {5}^{x}$ is unable to reach zero, as $x \to - \infty$ $y \to 0$, and since it is $- f \left(x\right)$ all values will be negative. Range: $f \left(x\right) < 0$