how do i integrate this? : t / (t+88) ?? i could rewrite it like this : 1 - (88/t+88) but i dont know how to integrate that. i dont think i can substitude anything.

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- Feb 11th 2013, 10:46 AMLevaniCan somebody help me on integration?
how do i integrate this? : t / (t+88) ?? i could rewrite it like this : 1 - (88/t+88) but i dont know how to integrate that. i dont think i can substitude anything.

- Feb 11th 2013, 11:06 AMMathJackRe: Can somebody help me on integration?
let u = t + 88, then, du = dt,

so expression is now (u-88)/u .du, or (1 - 88/u)du

now this is simple to integrate.

dont forget to sub back in after integration - Feb 11th 2013, 11:07 AMebainesRe: Can somebody help me on integration?
Substitute u = t+88:

t = u-88

du = dt

$\displaystyle \int \frac {t}{t+88} dt = \int \frac {u-88}{u} du = \int (1 - \frac {88} u) du $

$\displaystyle = u - 88 \ln (u) = t+88-88 \ln (t+88)$ - Feb 11th 2013, 11:21 AMLevaniRe: Can somebody help me on integration?
thank u but i dont get how did u go from INT( 1 - 88/u ) du to u - 88*ln(u) ?

which formula did u use, i cant find it on integral table - Feb 11th 2013, 11:25 AMMathJackRe: Can somebody help me on integration?
factor out 88 so u have 88(int) 1/u which is in is the natural log of u. In tables too. Please thank me

- Feb 11th 2013, 11:40 AMLevaniRe: Can somebody help me on integration?
oh i got it :D u take 88 out of integral