# Thread: Very Simple Question on l'Hopital's Rule

1. ## Very Simple Question on l'Hopital's Rule

So I am doing a limit for class

Lim x-> 0 1-cosx / x^2

I took the derivative which was sinx/2x

Then took the derivative again to get cosx/2 = 1/2

Do I wrote the answer as just 1/2 or do I write lim x->0 = 1/2?

I am asking because my professor is very picky and would definitely mark points off if I do it wrong.

I think I should write lim x -> 0 = 1/2

2. Originally Posted by KarlosK
So I am doing a limit for class

Lim x-> 0 1-cosx / x^2

I took the derivative which was sinx/2x

Then took the derivative again to get cosx/2 = 1/2

Do I wrote the answer as just 1/2 or do I write lim x->0 = 1/2?

I am asking because my professor is very picky and would definitely mark points off if I do it wrong.

I think I should write lim x -> 0 = 1/2
don't get lazy when writing limits ...

$\lim_{x \to 0} \frac{1-\cos{x}}{x^2} =$

$\lim_{x \to 0} \frac{\sin{x}}{2x} =$

$\lim_{x \to 0} \frac{\cos{x}}{2} = \frac{1}{2}$