Hey guys, I have a algebra question here.

So I have f(x) = ln x @ closed interval [1, 4]
According to the Mean Value theorem:
if ln x can be differentiated and is continuous, then:
f'(c) = [f(b) - f(a)] / b - a

So i get f(c) = (ln 4 - ln 1) / 3 = ln 4 / 3

However my book says: 3 / ln 4

I think i am missing an algebraic rule or something can you please help.

Question

Hey guys, I have a algebra question here.

So I have f(x) = ln x   @ closed interval [1, 4]
According to the Mean Value theorem: 
if ln x can be differentiated and is continuous, then:
 f'(c) = [f(b) - f(a)] / b - a

So i get f(c) = (ln 4 - ln 1) / 3 = ln 4 / 3

However my book says: 3 / ln 4

I think i am missing an algebraic rule or something can you please help.

anonymous · Answer

Right now you have:$$f'(c)=\frac{\ln 4}{3}$$If f(x)=ln x, then what is f'(x)?

anonymous · Answer

What is the derivative of ln x?

hero · Answer

@wakoff, finding f'(x) is the key to figuring it out.

anonymous · Answer

O shoot, i totally understand now thanks so much! I went to doze off for a bit! ty!