## memorizing integrals

AriAstronomer
Posts: 76
Joined: Thu May 12, 2011 4:53 pm

### memorizing integrals

Is it important to memorize some integrals, e.g. dx/(x^2 + a^2)^1/2 = ln(x + (x^2 + a^2)^1/2)?

If yes, which other ones do you think are relevant? xdx/(x^2 + a^2)^1/2. Any others?
Thanks,
Ari

HappyQuark
Posts: 762
Joined: Thu Apr 16, 2009 2:08 am

### Re: memorizing integrals

AriAstronomer wrote:Is it important to memorize some integrals, e.g. dx/(x^2 + a^2)^1/2 = ln(x + (x^2 + a^2)^1/2)?

If yes, which other ones do you think are relevant? xdx/(x^2 + a^2)^1/2. Any others?
Thanks,
Ari
I don't recall ever using a single memorized integral in any of the 4 practice tests or any of the real exams. Every instance in which an integral is ever necessary it could either be solved explicitly and was trivial to do so or they clearly meant for you to be making approximations (i.e. drawin' boxes under the curve).

On the other hand, I do recall a number of times in which memorizing some of the more obscure trig identities was necessary.

WhoaNonstop
Posts: 853
Joined: Mon Sep 21, 2009 1:31 am

### Re: memorizing integrals

No.

All you need to know for the physics GRE is what Positronium is.

-Riley

physicsworks
Posts: 80
Joined: Tue Oct 12, 2010 8:00 am

### Re: memorizing integrals

and use the process of elimination! 