Math Tutor wrote:Factor the numerator as a difference of squares: [tex]x-9=(\sqrt{x}-3)(\sqrt{x}+3)[/tex].
For [tex]x \neq 9[/tex] the factor [tex]\sqrt{x}-3[/tex] cancels:
[tex]\frac{x-9}{\sqrt{x}-3}=\frac{(\sqrt{x}-3)(\sqrt{x}+3)}{\sqrt{x}-3}=\sqrt{x}+3[/tex]
Hence [tex]\lim_{x \to 9}\frac{x-9}{\sqrt{x}-3}=\sqrt{9}+3=6[/tex].
(Same thing: multiply top and bottom by the conjugate [tex]\sqrt{x}+3[/tex].)
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