please help with this limit! i don’t understand it.
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Factorize the numerator as a difference of squares:
[tex]x-s=(\sqrt x)^2-(\sqrt s)^2=(\sqrt x-\sqrt s)(\sqrt x+\sqrt s)[/tex]
Then
[tex]\displaystyle\lim_{x\to s}\frac{x-s}{\sqrt x-\sqrt s}=\lim_{x\to s}(\sqrt x+\sqrt s)=\boxed{2\sqrt s}[/tex]