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Mathematics 14 Online
rvc (rvc):

please help

rvc (rvc):

\[\int\limits \log(logx+2)dx\]

rvc (rvc):

@rational

Parth (parthkohli):

i'm thinking integration by parts.\[\int \ln (\ln x + 2) dx = x\ln(\ln x + 2) - \int x\cdot \frac{1}{\ln x+2}\cdot\frac{1}{x} dx\]

rvc (rvc):

i think we have to do by substitution im not getting what to subsitute

OpenStudy (jhannybean):

LIATE or LIPETs for usub.

Parth (parthkohli):

u = ln(lnx + 2) and dv = dx

rvc (rvc):

hey jhaanybean whats P?

OpenStudy (jhannybean):

LIATE Log > inverse > algebraic (polynomials) > Trig > Exponential LIPETs Log > Inverse > Polynomials (algebraic) > Exponential > Trig

Parth (parthkohli):

Algebraic expressions are not necessarily polynomials.

OpenStudy (jhannybean):

Pick your poison.

OpenStudy (jhannybean):

Well true... but in this little acronym that's what theyre categorized as. that's why I stick with LIATE.

rvc (rvc):

i knew only about LIATE

OpenStudy (jhannybean):

\(\color{blue}{\text{Originally Posted by}}\) @ParthKohli i'm thinking integration by parts.\[\int \ln (\ln x + 2) dx = x\ln(\ln x + 2) - \int x\cdot \frac{1}{\ln x+2}\cdot\color{red}{\frac{1}{x}} dx\] \(\color{blue}{\text{End of Quote}}\) Haha I just had a brain fart and forgot about this little bugger.

Parth (parthkohli):

@rvc Where did you get this problem?

Parth (parthkohli):

The second integral is not expressible in elementary terms.

Parth (parthkohli):

Yeah, I checked WolframAlpha and it's the Ei function.

OpenStudy (kainui):

either \(\int\limits \log(\log(x+2))dx \text{ or } \int\limits \log(\log(x)+2)dx\) you're in trouble haha. You can still integrate this though with a power series.

rvc (rvc):

wait sorry i made a mistake in posting its logxlog(x+2)

Parth (parthkohli):

Oh my...

OpenStudy (jhannybean):

Let's start over.

rvc (rvc):

im extermely sorry guys yes lets start

rvc (rvc):

hmm so what to substitute

Parth (parthkohli):

OK, nope. I tried it all and this integral is also pretty hard.

rvc (rvc):

@rational here help

Parth (parthkohli):

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