Answer
a.$\sqrt {\frac{1}{4}-\frac{r}{18500}}=g^{-1}(r)$
b.$g^{-1}(30)=0.4984$
Work Step by Step
$V=g(r)=18500(0.25-r^2)$,
a.
$r=18500(0.25-V^2)$,
$r=4625-18500V^2$,
$V^2=\frac{1}{4}-\frac{r}{18500}$,
$V=\sqrt {\frac{1}{4}-\frac{r}{18500}}=g^{-1}(r)$
$g^{-1}(r)$ represents the radius of the artery as a function of its blood-moving velocity.
b.
$\sqrt {\frac{1}{4}-\frac{30}{18500}}=g^{-1}(30)$,
$g^{-1}(30)=0.4984$, represents the radius of the artery as a function of its speed equal to $30$.
