calculus problem

[RobDowneyJr]

how do i integrate:
ln (x+x^2) dx
anyone know?

 

[snik]

Open up your book and look there. Why do people expect Atot to do their homework?

 

[onza]

TI-89

===

but on a serious note, i think you ahve to integrate outside then inside, so integral of ln is 1/(xxxxxxx)

then + integral of inside..

but i cant remember, been like 2 yrs

 

[DrPizza]

integration by parts... (integral of udv = uv - integral of v du)
let u = the whole thing, dv = dx...


Sheeeesh, 7 minutes before anyone replied with the method. 🙂 Must be I'm the only calculus teacher on ATOT at this time?

 

[RobDowneyJr]

Originally posted by: snik
Open up your book and look there. Why do people expect Atot to do their homework?

The only reason i ask is because i cant find in my book, and im studying for final not doin hw

 

[MacBaine]

Because it's addition, you do each part on it's own (x -> 1/2x^2, x^2 -> 1/3x^3), then just put them both together.

Edit: nm, I didn't see the LN there 😱

 

[Rkonster]

Integration by parts.

 

[DrPizza]

Originally posted by: DrPizza
integration by parts... (integral of udv = uv - integral of v du)
let u = the whole thing, dv = dx...


Sheeeesh, 7 minutes before anyone replied with the method. 🙂 Must be I'm the only calculus teacher on ATOT at this time?

let u = ln (x + x^2)
then, du = 1/(x + x^2) * (1 + 2x)dx
dv = dx
then v = x
integral udv = uv - integral v du
= x ln(x + x^2) - integral x*(1 + 2x) dx / (x + x^2)