Help me figure out why I'm getting this extraneous solution

Questions
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1

Here is the link for the problem I did on wolfram, it tells me that x equals 3 and -5, but -5 is selected as the actual answer, but I dont understand why?

http://www.wolframalpha.com/input/?i=%E2%88%9A%284-x%29%2B%E2%88%9A%28x%2B6%29%3D4

2

Hi. Can you clarify what you mean?

Wolfram|Alpha provides both answers (3 and -5) to the equation. Both numbers solve the equation.