# How do you use part I of the Fundamental Theorem of Calculus to find the derivative of #f(x) = int {1} / {1+t^{2}} dt# from x to 5?

##### 1 Answer

#### Answer:

See the explanation section.

#### Explanation:

FTC 1 says (among other things) that if

If you meant

(which is read "the integral from

the

If you really meant the integral from

**Note 1**

In some ways, the hardest part of the FTC1 question on an exam is convincing yourself that is really is that easy!

**Note 2**

Some courses apparently give a slightly different version of Part 1 of the FTC.

For

we get

So you may see that sometimes here on Socratic.