Answer
$r(4)\approx10.498$
$r(-.5)=r(-\frac{1}{2})$
$r(-\frac{1}{2})\approx.745$
Work Step by Step
$r(w)=1.8^{w}$
$r(4)=1.8^{4}$
$r(4)\approx10.498$
$r(-.5)=r(-\frac{1}{2})=1.8^{-\frac{1}{2}}$
$r(-\frac{1}{2})=\frac{1}{\sqrt 1.8}$ (This is because $a^{-b}=\frac{1}{a^{b}}$ and $a^{\frac{1}{2}}=\sqrt a$)
$r(-\frac{1}{2})\approx.745$ (You could rationalize the fraction but it isn't necessary).
