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Thread: Integration using substitution

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    Cadet cloud edwards's Avatar
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    Integration using substitution

    Question: (refer to attachment), Evaluate the intergral using u=x^4 -3.

    I did this question without subbing in the x=0 & x=1 and got a fairly reasonable answer being: 211/20. I also checked with a couple of online integration calculators.

    HOWEVER,
    I realized i was supposed to sub in the x values into u=x^4-3 to get the boundaries. But when i did this, i got a ridiculous number being: -174,000 something.

    PLEASE HELP!!!
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    Re: Integration using substitution

    Quote Originally Posted by cloud edwards View Post
    Question: (refer to attachment), Evaluate the intergral using u=x^4 -3.

    I did this question without subbing in the x=0 & x=1 and got a fairly reasonable answer being: 211/20. I also checked with a couple of online integration calculators.

    HOWEVER,
    I realized i was supposed to sub in the x values into u=x^4-3 to get the boundaries. But when i did this, i got a ridiculous number being: -174,000 something.

    PLEASE HELP!!!





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    Re: Integration using substitution

    let u = x^4 - 3 when x=0 u = -3 when x = 1 u=-2

    So in your substituted work, you have to change the limits of integration to -3 and -2 resp.

    Or you can do it my way without substitution:

    Last edited by Drongoski; 17 Jun 2017 at 9:01 PM.
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    Re: Integration using substitution

    Thanx guys!

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