Integrating with Substitution: Solving for ∫(3x^2+x)(2x^3+x^2)^2 dx

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Homework Help Overview

The discussion revolves around the integration of the expression ∫(3x^2+x)(2x^3+x^2)^2 dx, focusing on the use of substitution methods in calculus.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the substitution of (2x^3+x^2) and the subsequent steps involving the differential dt. There is uncertainty about how to proceed after the substitution and how it relates to the integral form involving u.

Discussion Status

Some participants have provided guidance on the substitution process and clarified the relationship between the differentials. There appears to be a growing understanding among participants, although not all aspects have been fully resolved.

Contextual Notes

Participants express confusion regarding the transition from the substitution to the integral form, particularly in understanding the factor of 1/2 in the integral expression.

Nanu Nana
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Homework Statement


dz/dx=(3x2+x)(2x^3+x^2)^2[/B]

Homework Equations



∫(3x^2+x)(2x^3+x^2)^2 dx

The Attempt at a Solution


I tried substituting (2x^3+x^2)
Let t= 2x^3 + x^2
dt=6x^2+2x dx
dt/dx= 6x^2+2x
I can only solve till this point . I don't have any clue how to solve it further
But how do we get 1/2 ∫u^2 du ?? I don't understand it at all
 
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Nanu Nana said:

Homework Statement


dz/dx=(3x2+x)(2x^3+x^2)^2[/B]

Homework Equations



∫(3x^2+x)(2x^3+x^2)^2 dx

The Attempt at a Solution


I tried substituting (2x^3+x^2)
Let t= 2x^3 + x^2
dt=6x^2+2x dx
dt/dx= 6x^2+2x
I can only solve till this point . I don't have any clue how to solve it further
But how do we get 1/2 ∫u^2 du ?? I don't understand it at all

Let u = 2x^3 + x^2
=> du = (6x^2 + 2x)dx
=> du = 2(3x^2 + x)dx
=> du/2 = (3x^2 + x)dx

Thus, the integral becomes what you need.
 
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Likes   Reactions: Nanu Nana
Nanu Nana said:

Homework Statement


dz/dx=(3x2+x)(2x^3+x^2)^2[/B]

Homework Equations



∫(3x^2+x)(2x^3+x^2)^2 dx

The Attempt at a Solution


I tried substituting (2x^3+x^2)
Let t= 2x^3 + x^2
dt=6x^2+2x dx
dt/dx= 6x^2+2x
I can only solve till this point . I don't have any clue how to solve it further
But how do we get 1/2 ∫u^2 du ?? I don't understand it at all
Well, you used t as a variable rather than u, but that's unimportant.

Looking at Math_QED's post, the main thing your solution is lacking is that you should factor a 2 out of the right hand side of ##\ dt=(6x^2+2x) dx \ .##
 
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Likes   Reactions: Nanu Nana
Thank you both . I think i understand it now :)
 

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