Khan/khan-exercises — Issue #13277: Factoring difference of squares 2 - problem doesn't allow constant to be factored out
Author: KhanBugz
Created: 2012-02-07 18:13:29+00:00
State: open
Labels: ie8, ie9, win7, wrong-or-unclear

Reporter: joespiff@hotmail.com

the problem was to factor 36x^2 - 4. I said 4(3x+1)(3x-1), and the correct answer was (6x+2)(6x-2). If we are not to factor out constants, then either the problem generator needs to filter out problems that have a constant factor, or there needs to be a more explicit warning in the acceptable answer formats. If I had put (3x+1)(12X-4) then that would have been just as correct as the answer that the solution offered.

[factoring_difference_of_squares_2.html?seed=39&problem=0](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/factoring_difference_of_squares_2.html?seed=39&problem=0&debug)

[Answer timeline](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/factoring_difference_of_squares_2.html?seed=39&problem=0&debug&activity=%5B%5B%22incorrect-activity%22%2C%22%5B%5C%224(3x%2B1\)(3x-1\)%5C%22%5D%22%2C36%5D%2C%5B%22hint-activity%22%2C%220%22%2C3%5D%2C%5B%22hint-activity%22%2C%220%22%2C5%5D%2C%5B%22hint-activity%22%2C%220%22%2C6%5D%2C%5B%22hint-activity%22%2C%220%22%2C7%5D%2C%5B%22hint-activity%22%2C%220%22%2C7%5D%5D)

[["4(3x+1)(3x-1)"]]

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