Hi,

I've been learning Maths by myself and I got stuck with the Leibniz formula. The theory is as follows:

"Lets suppose that both partial derivatives of f(t,x) exist and that a(t) and b(t) are derivable functions and *F* (*t*)*.*

*F* (*t*) = ∫*b*(*t*)*a*(*t*) *f* (*t*, *x*) *d**x* for all *t*.

Then *F* '(*t*) = *f* (*t*, *b*(*t*))*b*'(*t*) − *f* (*t*, *a*(*t*))*a*'(*t*) + ∫*b*(*t*)*a*(*t*) *f* 1'(*t*, *x*) *d**x*.

So, I donīt completely understand the formula and I got my exercises wrong once and again. Please, could you explain step by step how to do it? I'll write you below and exercise and my attempt to get a) done.

For example: Find F'(t) in the following examples:*a) F* (*t*) = ∫*2**t**t* *x*2 [squared x] *d**x* .

**b)** F(t)= ∫*2**1* (e*tx*)/x *d**x*

What I did in a)

F'(t)= (2t)*2**2 - (t)*2* + ∫2*t**t* 2*x dx -->*

--> 4t*2**2 - t*2* + ∫2*t**t* 2*x dx *

*--> *7t*2* + (2t)*2* - (t)*2*

--> 4t*2*

**ANSWER IN THE BOOK: **

F'(t)= (2t)*2**2 - (t)*2* = 7t*2*

ANY HELP WOULD BE REALLY APPRECIATED.

THANK YOU