If f’(5) = 3, find the
(f(x)-f(5))/(√x-√5)
limx-5

Question

If f’(5) = 3,  find the 
               (f(x)-f(5))/(√x-√5)
limx->5

anonymous · Answer

$$\LARGE \lim_{x\to5}\frac{f(x)-f(5)}{\sqrt x-\sqrt5}$$  I'll just rewrite it better, if this is what you meant...  (I don't know to solve it ! ...)  hope someone else helps you out. Good Luck !

anonymous · Answer

multipyly top and bottom by $\sqrt{x}+\sqrt{5}$

anonymous · Answer

thanks kreshnik again, I am too technically uncapable to use some latex editor.

anonymous · Answer

$$ \lim_{x\to5}\frac{f(x)-f(5)}{\sqrt x-\sqrt5}\frac{\sqrt x+\sqrt 5}{\sqrt x+\sqrt 5}$$
$$ \lim_{x\to5}\frac{f(x)-f(5)(\sqrt{x}+\sqrt{5})}{x-5}$$
$$f'(5)(\sqrt{5}+\sqrt{5})$$

anonymous · Answer

last line since 
$$ \lim_{x\to5}\frac{f(x)-f(5)}{ x-5}=f'(5)$$ by definition

anonymous · Answer

@satellite73 I didn't know that, I learned something new. Great job .