Integration- (Substitution Rule) Help

  • Thread starter jordan123
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  • #1
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Homework Statement


Alright heres the problem. Also it is a definite integral from A=0 and b = 1
[tex]\int (x^7)(x^4-1)^{1/3}[/tex]

Any help is good.
 

Answers and Replies

  • #2
HallsofIvy
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Well, what have you tried? There is only one subsitution that would make any sense and that is u= x4- 1. What do you get if you try that substitution?
 
  • #3
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A pretty obvious substitution to try is u= x4- 1. Then du= 4x3dx so you can separate that x7 into x4 x3, use the "x3 with dx (and never write an integral without the "dx") and then x4= u+ 1.
[tex]\int x^7(x^4-1)dx= \int (u+1)u^{\frac{1}{3}}du= \int (u^{\frac{4}{3}}+ u^{\frac{1}{3}}*du[/tex]
Ok right, exactly. And the new a and b would become a = -1 and b = 0 correct?
 
  • #4
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Thanks, I got it now!!1
 

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