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(\sqrt23-1)(\sqrt23+1)

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(\sqrt23-1)(\sqrt23+1) [#permalink] New post   12 Sep 2020, 09:35
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91% (00:36) correct 8% (00:34) wrong based on 12 sessions

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\((\sqrt{23}-1)(\sqrt{23}+1)(\sqrt{22}-1)(\sqrt{22}+1)=\)


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462
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Re: (\sqrt23-1)(\sqrt23+1) [#permalink] New post   28 Sep 2020, 21:38
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Basically this is a question in the form

\((x-y)(x+y)=x^2-y^2\)

So the first term will become \((\sqrt{23})^2-1^2=23-1=22\)

The second \((\sqrt{22})^2-1^2=22-1=21\)

\(22 \times 21=462\)
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Re: (\sqrt23-1)(\sqrt23+1) [#permalink]
28 Sep 2020, 21:38
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