Khan/khan-exercises — Issue #10869: Radical equations - Wrong solution in Radical Equations exercise
Author: KhanBugz
Created: 2012-01-10 18:09:49+00:00
State: open
Labels: chrome, wrong-or-unclear, xp

There's a problem in one of the answers for the Radical Equations exercise. According to the solution, -2 = sqr(x), or in other words -2 = x^(1/2), doesn't have an answer because the principle squareroot of a number cannot be negative. However, -2 is only the result of the principle squareroot of x, not x itself. To solve it, both sides of the equation merely have to be squared, so that -2^2 = (x^(1/2))^2 and thus x = 4.

[radical_equations.html?seed=112&problem=0](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/radical_equations.html?seed=112&problem=0&debug)

[Answer timeline](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/radical_equations.html?seed=112&problem=0&debug&activity=%5B%5B%22correct-activity%22%2C%22%5C%22No%20solution%5C%22%22%2C120%5D%5D)

["No solution"]

Mozilla/5.0 (Windows NT 5.1) AppleWebKit/535.7 (KHTML, like Gecko) Chrome/16.0.912.75 Safari/535.7

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