Integrating Brackets

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  1. buj's Avatar
    • Exalted Member
    • Location: uk
    • Posts: 341
    Integrating Brackets
    How do you integrate brackets.

    For example, (x-1)^-2

    any help appreciated.
  2. KSP's Avatar
    • PS Helper
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    • Location: London
    • Posts: 284
    Re: Integrating Brackets
    substitution? Ie, let u=x-1
  3. theflyingpig's Avatar
    • Exalted Member
    • Location: England
    • Posts: 265
    Re: Integrating Brackets
    u = x-1

    du/dx = 1

    dx = du

    integral u^-2 du

    = -u^-1
    = -(x-1)^-1
  4. 0129Hippy's Avatar
    • Benevolent Member
    • Location: Strathclyde
    • Posts: 637
    Re: Integrating Brackets
    Use the chain rule. Add one to the power, then divide the whole bracket by (the new power times by the dericitive of whats inside the bracket)....Thus giving you (x-1)^-1/-1
    Last edited by 0129Hippy; 10-06-2008 at 13:13.
  5. 0129Hippy's Avatar
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    • Location: Strathclyde
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    Re: Integrating Brackets
    (Original post by theflyingpig)
    u = x-1

    du/dx = 1

    dx = du

    integral u^-2 du

    = -u^-1
    = -(x-1)^-1
    You're right.
    Last edited by 0129Hippy; 10-06-2008 at 13:13.
  6. Daniel Freedman's Avatar
    • Overlord in Training
    • Posts: 2,331
    Re: Integrating Brackets
    (Original post by buj)
    How do you integrate brackets.

    For example, (x-1)^-2

    any help appreciated.
    If you don't want to use substitution, add one to the power to give  (x-1)^{-1} . If you then differentiate back again, you get  - (x-1)^{-2} , which is -1 times too big. We therefore need to divide what we differentiated by -1, giving the answer as  -(x-1)^{-1} .
  7. Cities's Avatar
    • TSR Idol
    Re: Integrating Brackets
    (Original post by 0129Hippy)
    You're wrong.
    Nope you need to revise. -2 + 1 does not equal -3
  8. Goldenratio's Avatar
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    • Location: Paree
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    Re: Integrating Brackets
    (Original post by 0129Hippy)
    You're wrong.
    No he's right.
  9. 0129Hippy's Avatar
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    • Location: Strathclyde
    • Posts: 637
    Re: Integrating Brackets
    Ooooopsies...I apologise will all my heart.
  10. uthred50's Avatar
    • Community Assistant
    • Rock 'n' Roll.
    Re: Integrating Brackets
    First two people were wrong.

    You get 1/(1-x)

    By doing it the way Daniel Friedman explained.
  11. Cities's Avatar
    • TSR Idol
    Re: Integrating Brackets
    (Original post by buj)
    How do you integrate brackets.

    For example, (x-1)^-2

    any help appreciated.
    you've left it quite late :eek:

    past papers are your friends
  12. Cities's Avatar
    • TSR Idol
    Re: Integrating Brackets
    (Original post by uthred50)
    Actually, you're both wrong.

    You get 1/(1-x)
    No you're wrong lol

    -(x-1)^-1 = 1/(1-x)
  13. uthred50's Avatar
    • Community Assistant
    • Rock 'n' Roll.
    Re: Integrating Brackets
    (Original post by n1r4v)
    No you're wrong lol

    -(x-1)^-1 = 1/(1-x)
    i was refering to the other dude, but like 3 people posted before i put that post lol

    The answer is definately 1/(1-x), whcih can also be phrased as (1-x)^-1
  14. medione's Avatar
    • Full Member
    • Location: london
    • Posts: 81
    Re: Integrating Brackets
    you can not integrate brackets....first of all you need to expand the braket... and then integrate.
  15. Daniel Freedman's Avatar
    • Overlord in Training
    • Posts: 2,331
    Re: Integrating Brackets
    (Original post by medione)
    you can not integrate brackets....first of all you need to expand the braket... and then integrate.
    You are wrong, unless you want to be forever integrating an infinite expansion....
  16. stordoff's Avatar
    • Exalted Member
    • Location: Sheffield
    • Posts: 268
    Re: Integrating Brackets
    (Original post by medione)
    you can not integrate brackets....first of all you need to expand the braket... and then integrate.
    Yes you can, substitution or chain rule.
  17. acsi's Avatar
    • Benevolent Member
    Re: Integrating Brackets
    If your revising for Edexcel Core 4 on Thursday you really should be able to do this by substitution or by observation by now.
  18. Goldenratio's Avatar
    • Exalted and Worshipped Member
    • Location: Paree
    • Posts: 1,308
    Re: Integrating Brackets
    we're all wrong. the answer is \displaystyle \pi...
  19. Cities's Avatar
    • TSR Idol
    Re: Integrating Brackets
    (Original post by louiscbrooks)
    If your revising for Edexcel Core 4 on Thursday you really should be able to do this by substitution or by observation by now.
    Do you have any more logic puzzles :p:
  20. acsi's Avatar
    • Benevolent Member
    Re: Integrating Brackets
    (Original post by n1r4v)
    Do you have any more logic puzzles :p:
    lol no
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