Radical equality

dmouthfan2028

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Feb 18, 2010
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Is 322+1=2\displaystyle \sqrt{3-2\sqrt{2}}+1 = \sqrt{2} ? If so, why? How can it be proven?
 
Hello, dmouthfan2028!

Is 322+1=2 ?\displaystyle \text{Is }\sqrt{3-2\sqrt{2}}+1 \:=\: \sqrt{2}\text{ ?}

If so, why?  How can it be proven?\displaystyle \text{If so, why? }\:\text{ How can it be proven?}

We have: x  =  322+1\displaystyle \text{We have: }\:x \;=\;\sqrt{3-2\sqrt{2}} + 1


Note that: 322  =  (21)2\displaystyle \text{Note that: }3- 2\sqrt{2} \;=\;(\sqrt{2}-1)^2


Hence: 322+1  =  (21)2+1  =  (21)+1  =  2\displaystyle \text{Hence: }\:\sqrt{3-2\sqrt{2}} + 1 \;=\;\sqrt{(\sqrt{2}-1)^2} + 1 \;=\;(\sqrt{2}-1) + 1 \;=\;\sqrt{2}

 
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