Khan/khan-exercises — Issue #12336: Algebra challenge - x_1 irrelevant when slope is zero
Author: KhanBugz
Created: 2012-01-28 02:48:56+00:00
State: open
Labels: firefox, wrong-or-unclear

Reporter: walck@lvc.edu

When slope of a line is zero, any value of x_1 will satisfy y-y_1 = m(x-x_1). It is unreasonable to expect a person to supply only one of the given values for x_1.

[algebra_challenge.html?seed=70&problem=y-as-function-of-x (point_slope_form)](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/algebra_challenge.html?seed=70&problem=y-as-function-of-x&debug)

[Answer timeline](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/algebra_challenge.html?seed=70&problem=y-as-function-of-x&debug&activity=%5B%5B%22incorrect-activity%22%2C%22%5B%5B%5C%221%5C%22%2C%5C%220%5C%22%2C%5C%22%5C%22%5D%5D%22%2C22%5D%2C%5B%22incorrect-activity%22%2C%22%5B%5B%5C%221%5C%22%2C%5C%220%5C%22%2C%5C%220%5C%22%5D%5D%22%2C32%5D%2C%5B%22hint-activity%22%2C%220%22%2C78%5D%2C%5B%22hint-activity%22%2C%220%22%2C96%5D%2C%5B%22hint-activity%22%2C%220%22%2C102%5D%2C%5B%22hint-activity%22%2C%220%22%2C105%5D%5D)

[[["1","0",""]],[["1","0","0"]]]

Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.18) Gecko/20110628 Ubuntu/10.04 (lucid) Firefox/3.6.18

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