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AP® Calculus AB-BC

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Moderate

Decreasing Derivative

APCALC-Y4RIEO

$f^{ \prime \prime }( x ) ={ x }^{ 3 }-\cfrac{{ 2x }^{ 2 }}{x-1} .$ On what intervals is $f^\prime(x)$ decreasing?

A

$(-1,2)$

B

$(1,2)$

C

$(-\infty,-1)$ and $(1,2)$

D

$(-1,1)$