Khan/khan-exercises — Issue #9169: Chain rule 1 - Chain Rule 1- "Wrong" answer is actually correct
Author: KhanBugz
Created: 2011-12-21 06:46:55+00:00
State: open
Labels: firefox, other, win7

Reporter: nessrockz305@yahoo.com

The question in hand is:
Let g(x)=(x4)^4
g′(x)=?
where one of the answer choices is (−4(x^4)^3)(−4x^3). This is equivalent to the actual answer given of (4(x^4)^3)(4x^3) as clearly the double negative does not matter. Both of these equal 16*x^15 which is the clear answer when simplified.

[chain_rule_1.html?seed=148&problem=0](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/chain_rule_1.html?seed=148&problem=0&debug)

[Answer timeline](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/chain_rule_1.html?seed=148&problem=0&debug&activity=%5B%5B%22incorrect-activity%22%2C%22%5C%22%3Ccode%20style%3D%5C%5C%5C%22display%3A%20none%3B%5C%5C%5C%22%3E(-4(x%5E%7B4%7D\)%5E%7B3%7D\)(-4x%5E%7B3%7D\)%3C%2Fcode%3E%5C%22%22%2C12%5D%2C%5B%22correct-activity%22%2C%22%5C%22None%20of%20the%20above.%5C%22%22%2C73%5D%5D)

["(-4(x^{4})^{3})(-4x^{3})","None of the above."]

Mozilla/5.0 (Windows NT 6.1; WOW64; rv:8.0) Gecko/20100101 Firefox/8.0

MathJax is loaded, ready, queue length: 0