How do i find integral of this
Welcome to the form.
You look it up in a table or use a CAS.
You will not be able to do it by hand, because there is no closed form in terms of elementary functions.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.