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I was going through some problems and I came across this one, it said to see if the fuction below is derivable in the point [tex]x_{0}=1^{-}[/tex]

[tex]f(x)=\frac{x+1}{1-\sqrt{1-x}}[/tex]

so I did this as usual,

limit of [tex]\frac{f(x)-f(1)}{x-1}[/tex] when x -> 1, and x<1 is equal to the limit of:

[tex]\frac{x-1+2\sqrt{1-x}}{(x-1)(1-\sqrt{1-x}}[/tex]

but I really don't know what to do after!! I tried to multiply the top and bottom with "x+2sqrt(1-x)" but with no satisfying results.

Any help would be appreciated!

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# Homework Help: Derivable function

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