PLEASE HELP!!!
Identify a function f and a point x = a for which the given limit represents f '(a).
lim as x approaches -4
((sqrt. 29+x) -5) / (x+4)

Question

PLEASE HELP!!!
Identify a function f and a point x = a  for which the given limit represents f '(a).
lim as x approaches -4
((sqrt. 29+x) -5) / (x+4)

anonymous · Answer

there are two parts: 
f(x)= ?
a= ?

zepdrix · Answer

Ummm, here is a form of the limit definition of the derivative that is less frequently used,
$$\lim_{x \rightarrow a}\frac{ f(x)-f(a) }{ x-a }$$
Now let's compare that to the equation we were given,
$$f'(a) =\lim_{x \rightarrow -4}\frac{ \sqrt {29+x} -5}{ x+4 }$$
Hmmm they look kind of similar, can you see the f(x) and a? :)

anonymous · Answer

wow. i totally didn't notice. i was doing it all by hand but i still couldn't come up with it. but thanks!!!

zepdrix · Answer

^^