[Toán 9] SO SÁNH

B

baochauhn1999

Ta có:
$(\sqrt{2010}-\sqrt{2009})(\sqrt{2010}+\sqrt{2009})=2010-2009=1$
$(\sqrt{2009}-\sqrt{2008})(\sqrt{2009}+\sqrt{2008})=2009-2008=1$
$=>(\sqrt{2010}-\sqrt{2009})(\sqrt{2010}+\sqrt{2009})=(\sqrt{2009}-\sqrt{2008})(\sqrt{2009}+\sqrt{2008})$
Mà:
$\sqrt{2010}+\sqrt{2009}$>$\sqrt{2009}+\sqrt{2008}$
Nên:
$\sqrt{2010}-\sqrt{2009}$<$\sqrt{2009}-\sqrt{2008}$
 
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