Don't know if this is correct (and final step)

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Homework Help Overview

The discussion revolves around evaluating the integral \(\int_0^1 \frac{4\ln(3x)}{\sqrt{x}}dx\), with participants exploring the correctness of their approaches and results. The subject area includes calculus, specifically integration techniques and logarithmic functions.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants describe their attempts at solving the integral using integration by parts and express uncertainty about their final results. There are questions regarding discrepancies between their calculations and those provided by computational tools like Wolfram Alpha.

Discussion Status

Some participants have confirmed the correctness of the indefinite integral steps but are still questioning the final evaluation. There is an ongoing exploration of the differences in results from various calculators and software.

Contextual Notes

Participants note potential confusion regarding the interpretation of logarithmic functions, specifically the distinction between natural logarithm (ln) and common logarithm (log10), which may affect their results.

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Homework Statement


\int_0^1 \frac{4ln(3x)}{\sqrt{x}}dx


Homework Equations





The Attempt at a Solution


I really don't want to type all this out, but since I hate when people don't, I will. I hope someone takes the time to help me out :)

\int_0^1 \frac{4ln(3x)}{\sqrt{x}}dx=\lim{t \to 0^{+}} \int_0^{t} \frac{4ln(3x)}{\sqrt{x}}dx
u=4ln3x, v=2\sqrt{x}\\du=\frac{4}{x}dx, dv=\frac{1}{\sqrt{x}}dx
(4ln3x)(2\sqrt{x})-\int \frac{8\sqrt{x}}{x}dx=8\sqrt{x}(ln3x)-8\int x^{\frac{-1}{2}}dx=8\sqrt{x}(ln3x)-16\sqrt{x}
\lim_{t \to 0^{+}} (8\sqrt{x}(ln3x)-16\sqrt{x})|_{t}^{1}=\lim_{t \to 0^{+}} 8(ln3)-16-(8\sqrt{t}(ln3t)-16\sqrt{t})

Now I think that just equals 8ln3-16, but I'm not sure and wolfram gives me a different answer..

Thanks.
 
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iRaid said:

Homework Statement



\displaystyle \int_0^1 \frac{4\ln(3x)}{\sqrt{x}}dx

Homework Equations



The Attempt at a Solution


I really don't want to type all this out, but since I hate when people don't, I will. I hope someone takes the time to help me out :)
\int_0^1 \frac{4\ln(3x)}{\sqrt{x}}dx=\lim_{t \to 0^{+}} \int_0^{t} \frac{4\ln(3x)}{\sqrt{x}}dx<br /><br /> u=4\ln3x, v=2\sqrt{x}\\du=\frac{4}{x}dx, dv=\frac{1}{\sqrt{x}}dx<br /><br /> (4\ln3x)(2\sqrt{x})-\int \frac{8\sqrt{x}}{x}dx=8\sqrt{x}(\ln3x)-8\int x^{\frac{-1}{2}}dx=8\sqrt{x}(\ln3x)-16\sqrt{x}<br /><br /> \lim_{t \to 0^{+}} (8\sqrt{x}(\ln3x)-16\sqrt{x})|_{t}^{1}=\lim_{t \to 0^{+}} 8(\ln3)-16-(8\sqrt{t}(\ln3t)-16\sqrt{t})
Now I think that just equals 8ln3-16, but I'm not sure and wolfram gives me a different answer..

Thanks.
The indefinite integral is correct. (I've checked your work that far.)

What result does Wolfram give you?
 
SammyS said:
The indefinite integral is correct. (I've checked your work that far.)

What result does Wolfram give you?

Wow I'm stupid I just did it again and I'm not sure why wolfram gives me the answer, but my calculator gives me a different answer?? Log=ln right?
 
iRaid said:
Wow I'm stupid I just did it again and I'm not sure why wolfram gives me the answer, but my calculator gives me a different answer?? Log=ln right?
That's true for Wolfram.

For you calculator, it's probably log = log10 .
 
SammyS said:
That's true for Wolfram.

For you calculator, it's probably log = log10 .

That is so stupid -.-"
 

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