Khan/khan-exercises — Issue #4713: Chain rule 1 - Chain rule, cos^3(x). Same answeer twice.
Author: KhanBugz
Created: 2011-10-21 11:16:37+00:00
State: open
Labels: firefox, snowleo

The correct answer also appears among the incorrect answers, albeit in a different form.

Derivative of cos^3(x) is
3 cos^2(x) (-sin(x)),
but that equals
-3 cos^2(x) sin(x), which is an answer the machine ticks of as wrong.

[chain_rule_1.html?seed=136&problem=0](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/chain_rule_1.html?seed=136&problem=0&debug)

["(-3\\cos^{2} {x})(\\sin{x})","(3\\cos^{2} {x})(-\\sin{x})"]

Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:7.0.1) Gecko/20100101 Firefox/7.0.1

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