How Do You Solve an Integral Using Substitution?

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Homework Help Overview

The discussion revolves around solving an indefinite integral using substitution, specifically the integral of (square root 2 + lnx) / x with respect to x.

Discussion Character

  • Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants describe their attempts at using substitution, defining u as 2 + ln(x) and differentiating to find du. There are questions regarding the correctness of the final expression derived from the integral.

Discussion Status

Some participants have provided similar solutions and are questioning the accuracy of their final results. There appears to be a productive exchange regarding the details of the calculations, with some affirmations of correctness noted.

Contextual Notes

There is a mention of a potential oversight in the final expression, indicating that participants are critically examining their work and the assumptions made during the substitution process.

rowdy3
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Use substitution to find each indefinite integral.
∫ (square root 2 + lnx) / x ; dx
I did
u=2+ln(x)
then differentiate both sides to get
du=0+dx/x
∫ (square root 2 + lnx) / x ; dx
∫ (square root u) du
∫ u^0.5 du
u^(3/2)/(3/2)+c
=(2+ln(x))^(3/2) +c
Is the answer right? Thanks.
 
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rowdy3 said:
Use substitution to find each indefinite integral.
∫ (square root 2 + lnx) / x ; dx
I did
u=2+ln(x)
then differentiate both sides to get
du=0+dx/x
∫ (square root 2 + lnx) / x ; dx
∫ (square root u) du
∫ u^0.5 du
u^(3/2)/(3/2)+c
=(2+ln(x))^(3/2) +c
Is the answer right? Thanks.

It was until you left out something in the last line.
 
(2/3)*[2+lnx]^(3/2)+C. Is that right?
 
Last edited:
rowdy3 said:
(2/3)*[2+lnx]^(3/2)+C. Is that right?

Yes, it is.
 

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