# How to integrate K/[(y^2 + K)^3/2] dy

1. Sep 24, 2011

### animboy

As you can see the function given is

K/[(y2 + K)1.5]

The integral of this equation with respect to dy is part of the explanation my textbook gives of finding electric field due to line of uniformly charged wire, where y of course is the variable length of the wire. Then it gives the integral as

y/[d(y2 + k2)0.5]

but I can't see how it got this, since I try to differentiate this answer and got back this function which was different to the original.

Can someone whow me how the text book got that answer? Thanks.

Here is a picture of the original textbook statement.

[PLAIN]http://desmond.imageshack.us/Himg97/scaled.php?server=97&filename=physicsq.png&res=medium [Broken]

Last edited by a moderator: May 5, 2017
2. Sep 24, 2011

### Rayquesto

integrate ((y^2 + K)^-3/2)dy=dv to get -((y^2 + K)^-1/2)/y=v

then

multiply that times K and you should be able to get the right answer since K is constant right?

this is just what I think

3. Sep 24, 2011

### animboy

Never mind, I found out what I did wrong. I misused the product rule. What a simple mistake.