Sunday, 21 December 2014

algebra precalculus - Is |x|cdot|x|=|x2|=x2?




Is |x||x|=|x2|=x2 ?




I'm very sorry if this question is a duplicate but I couldn't find anything about it (most likely because it's wrong..). But I'm not sure if this is correct so I need to ask you.



|x||x|=|x2| should be alright




Now my confusion starts. x2 should be positive / neutral for any value. That would mean we can ignore the absolute value sign? On the other hand we could have that |x2|. But that would be a different thing than |x2|, they are not equal to each other...? Please help me if I do this little thing wrong the entire task will be wrong. I got some thinking error here..



When there is the same question (I couldn't find one), please link me to it and I will delete this one immediately.


Answer



You are thinking it too hard. You could just look at the definition of the absolute value
|x|:={x,x0x,x<0


and check on your own that |x|2=|x2|=x2.






In general, we have |a||b|=|ab|, which is true also for complex numbers; but the identity |x2|=x2 is not necessarily true in the complex world.


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