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    could someone explain how do i finish this problem? or have i got it all wrong? thank you
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    (Original post by smelborp)
    could someone explain how do i finish this problem? or have i got it all wrong? thank you
    Did you mean to put up some working? If so, I can't see it.
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    (Original post by smelborp)
    could someone explain how do i finish this problem? or have i got it all wrong? thank you
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    Have you been able to do the other parts? They all look quite similar. I would imagine one would use Maclaurin series expansions.
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    (Original post by Pangol)
    Have you been able to do the other parts? They all look quite similar. I would imagine one would use Maclaurin series expansions.
    yes i managed to do the other parts but i guess i'm missing something obvious on this one
    so far i have this,which i'm not sure it's correct
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    (Original post by atsruser)
    Did you mean to put up some working? If so, I can't see it.
    You may have noticed this already, but you have a sign error in the denominator of that working that you (briefly!) posted.
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    (Original post by smelborp)
    could someone explain how do i finish this problem? or have i got it all wrong? thank you
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    As a potential hint for the question that isn't crossed off:

    (\sqrt{2}+1)^2 = 2 + 2\sqrt{2}+1=3+2\sqrt{2}
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    (Original post by Pangol)
    You may have noticed this already, but you have a sign error in the denominator of that working that you (briefly!) posted.
    I haven't posted any working here unless I went into some kind of trance and have forgotten.
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    (Original post by atsruser)
    As a potential hint for the question that isn't crossed off:

    (\sqrt{2}+1)^2 = 2 + 2\sqrt{2}+1=3+2\sqrt{2}
    thank you,i did reach that part,but not sure what to do next,i posted a picture in reply to pangol but it's still being approved
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    (Original post by smelborp)
    thank you,i did reach that part,but not sure what to do next,i posted a picture in reply to pangol but it's still being approved
    The problem in your working wasn't this bit - you got this right - but what happens when you try to subtract it from 3 + 2x. You made a small sign error.
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    (Original post by smelborp)
    thank you,i did reach that part,but not sure what to do next,i posted a picture in reply to pangol but it's still being approved
    The point of the hint is that L'Hopital's rule will apply, if you want to use it.
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    (Original post by atsruser)
    The point of the hint is that L'Hopital's rule will apply, if you want to use it.
    i know about l'hopital's rule but i started the book from the beginning and i haven't reached that,so i want to learn how to do it without,and i remember my teacher telling me that when we have roots it's better to do it without the rule..
    just point me out in the right direction people,this is taking me way to much time
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    (Original post by smelborp)
    i know about l'hopital's rule but i started the book from the beginning and i haven't reached that,so i want to learn how to do it without,and i remember my teacher telling me that when we have roots it's better to do it without the rule..
    just point me out in the right direction people,this is taking me way to much time
    Do you know about rationalising the numerator?
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    (Original post by smelborp)
    just point me out in the right direction people,this is taking me way to much time
    You just need to subtract the 3 + 2 root(2) correctly. It'll be easy then!
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    (Original post by Pangol)
    You just need to subtract the 3 + 2 root(2) correctly. It'll be easy then!
    so it's 3+2x-(3+2sqrt2) =>3+2x-3-2sqrt2 =>2-2sqrt2?
    then what? what am i not getting here ?
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    (Original post by smelborp)
    so it's 3+2x-(3+2sqrt2) =>3+2x-3-2sqrt2 =>2-2sqrt2?
    then what? what am i not getting here ?
    2x - 2sqrt2, not 2 - 2sqrt2. Then factorise out 2 from this, and write one of the parts in the denominator as the difference of two squares.
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    got it,god damn it so much time for this,if i could just see it resolved i'd understand it in a few seconds.
    thank you pangon and atsruser for your help
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    (Original post by smelborp)
    got it,god damn it so much time for this,if i could just see it resolved i'd understand it in a few seconds.
    thank you pangon and atsruser for your help
    Glad you got there. I found this interesting because I'd never seen that method before - I was assuming that you'd have to use the Maclaurin series expansion of root(3 + 2x) and take it from there.
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Size:  94.9 KB this is it,pangol.i haven't heard about maclaurin's series actually ;p maybe because i live in another country so it could be the same thing
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    (Original post by smelborp)
    pangol.i haven't heard about maclaurin's series actually ;p maybe because i live in another country so it could be the same thing
    No it's very different! Perhaps you'll learn about them soon, perhaps not... there is an awful lot of pure maths out there!
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    (Original post by smelborp)
    got it,god damn it so much time for this,if i could just see it resolved i'd understand it in a few seconds.
    thank you pangon and atsruser for your help
    What technique did you use for the others? I would have thought this would have worked for most of them. Anyway: well done!
 
 
 
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