Trying to understand an integration example

[OnceMore]

Hello.

I am having some trouble understanding an integration example we have. I have written it out in the attached pdf. I would be grateful if someone can help me undertand what is going on.

I assume you let a = (x-R_P)/(√2 ΔR_P) da to make the process easier, but I am, not sure how that becomes

1/(√2 ΔR_P) dx

I thought if we took the top line to be a constant, that should have come out as zero?

-S

 

[phyzguy]

You make the substitution a = (x-RP)/(√2 ΔRP) , then take the derivative of this with respect to x. Everything but x is treated as a constant, so this gives
da/dx = 1/(√2 ΔRP), or dx = (√2 ΔRP) da.

 

[OnceMore]

Hello,

Thanks for the reply. Right, yea, I think I understand that ...I will run through it a few times just to make sure.

Thanks.

-S