CPM Homework Help : CALC Problem 8-102

Multiple Choice: $\frac { d } { d x } [ \operatorname { arccos } ( 3 x ) ]$ =

$-\frac{3}{\sqrt{1-x^2}}$
$\frac { - 1 } { 3 \operatorname { sin } 3 x }$
$-\frac{3}{\sqrt{1-3x^2}}$
$-\frac{3}{\sqrt{1-9x^2}}$
$-\frac{3}{\sqrt{9x^2-1}}$

Hint:

Without jumping straight into the Chain Rule, you can figure this out. Visualize what the 3 does to the graph of y = arccosx? It will do the same thing to the slope function.