What are the local extrema of f(x)=(x-1)/(x-4)?

Nov 11, 2015

$f ' \left(x\right) = - \frac{3}{x - 4} ^ 2$
$f ' \left(x\right)$ is never $0$ and is undefined only at $x = 4$ which is not in the domain of $f$.
$f$ has no critical numbers, so $f$ has no local extrema.