Browse Questions

If $f(x)=\mid x-25\mid$ and $g(x)=f(f(x))$,find $g'(x)$ for $x > 50$

$(a)\;0\qquad(b)\;2\qquad(c)\;1\qquad(d)\;3$

$g(x)=f(f(x))=f(\mid x-25\mid)$
$\qquad\qquad\quad\;\;\;=\mid \mid x-25\mid-25\mid$
$\mid x-25-25\mid$ for $x > 50$
$\mid x-50\mid$ for $x > 50$
$x-50$
Hence $g'(x)=1$
Hence (c) is the correct answer.