Question

Use the definition of f′(a) (derivative) to compute f′(a) when
f(x) =4/(x+1)
and a = 2:

* * can i use this to solve this problem
limX-->a = f(x)-f(a)/X-a

Answer 1

you could use the limit method or you could just make f(x) = 4(x+1)^-1 and apply the product rule

Answer 2

but my friend told me that u have to use this one: lim h-->0 = f(a+h)-f(a)/h which one is right ???

Answer 3

both of those work.

Answer 4

are u sure ?? because i used the very first one for my math mid term and im like so depressed

Answer 5

yes they both work, do you want to see the proof?

Answer 6

no I trust U thanks my friend.