Khan/khan-exercises — Issue #9935: Radical equations - Incorrect Working Out (unless it is my misunderstanding)
Author: KhanBugz
Created: 2011-12-31 06:38:23+00:00
State: open
Labels: chrome, wrong-or-unclear, xp

Reporter: ericma3580@gmail.com

The topic is "Solving Radical Equations 1". I began the first question and couldn't quite seem to produce any answer that matched the options provided. The question was 4(√x)+5=8(√x)+8 and solve for x. Firstly, I moved the roots (radicals) to one side and the whole numbers to the other, as explained in your solution. This became −3=4(√x). I then divided both sides by 4, producing −3/4=√x. At this point, your solution says that it has no solution because "the principal root of a number cannot be negative". But it shouldn't be 'rooting' both sides, rather squaring them instead, isn't it? Please reply to me via my email if I am wrong (and please add an explanation). :)

[radical_equations.html?seed=30&problem=0](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/radical_equations.html?seed=30&problem=0&debug)

[Answer timeline](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/radical_equations.html?seed=30&problem=0&debug&activity=%5B%5B%22correct-activity%22%2C%22%5C%22No%20solution%5C%22%22%2C18%5D%5D)

["No solution"]

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