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i made a paradox but i am not sure if it is a real one.

\(-1^2=1\) but \(\sqrt{1}≠-1\)

 Jul 3, 2016
 #1
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it's not a real one.

 

First \(-1^2 = -1\) and it's not 1

 

Second, if you mean (-1)2 then it's all good, but the last part. If you solve the equation x2=1 ......

Method 1:

 

\(\color{red}x^2=1\)

\(\color{red}\sqrt{x^2}=\sqrt1\)

\(\color{red}x = \pm 1\)

 

Method 2:

\(\color{aqua}x^2=1\)

\(\color{aqua} x^2-1=0\)

\(\color{aqua}x = {-0 \pm \sqrt{0^2-4(1)(-1)} \over 2(1)}= \pm 1\)

 

Either ways show that \(\sqrt 1\) have 2 answers, 1 and -1. But to state clearly which answer do we mean, we use \(\sqrt1\) to denote 1 and \(-\sqrt1\) to denote -1. 

 Jul 4, 2016

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