Join TSR now and get all your revision questions answeredSign up now
    Offline

    15
    ReputationRep:
    (Original post by Myocardium)
    How would you integrate something like 3^x?
    Do you know how to differentiate it?
    Offline

    0
    ReputationRep:
    (Original post by justinawe)
    I think it would be pretty standard, though I'm not 100% sure about that.

    You could also easily integrate it using a substitution like u=x+1, btw.
    I used substitution and got this , it's wrong!

    What did I do wrong ?? Help ??

    Name:  ImageUploadedByStudent Room1371490410.611607.jpg
Views: 91
Size:  114.0 KB


    Posted from TSR Mobile
    Offline

    0
    ReputationRep:
    (Original post by m4ths/maths247)
    You are welcome.
    All the best for tomorrow and stay positive!
    Hey what did I do wrong with this question!! Help !!

    Name:  ImageUploadedByStudent Room1371490541.662260.jpg
Views: 114
Size:  120.6 KB


    Posted from TSR Mobile
    Offline

    0
    ReputationRep:
    (Original post by MasterYi)
    I have this which my teacher made. Has all the important ones.Attachment 227717
    Thanks a bundle!
    Offline

    0
    ReputationRep:
    (Original post by PythianLegume)
    Do you know how to differentiate it?
    Yes, it'd be 3^xln(3)?
    Offline

    3
    ReputationRep:
    (Original post by orange94)
    I used substitution and got this , it's wrong!

    What did I do wrong ?? Help ??

    Name:  ImageUploadedByStudent Room1371490410.611607.jpg
Views: 91
Size:  114.0 KB


    Posted from TSR Mobile
    That's correct, actually.

    Just in this case, you got 1+C instead of C. But when you really think about it, 1+C is still a constant anyway, so it doesn't matter.
    Offline

    15
    ReputationRep:
    (Original post by PhoenixSeeker)
    Can someone please explain why I can't integrate 3/cos x ^2 like this..?
    I understand the mark scheme and realise it is ALOT easier using that method (I just stupidly didn't spot sec x ^2)

    Attachment 227714
    You've integrated it wrong - it looks more like differentiation there.
    Offline

    2
    ReputationRep:
    (Original post by LegendX)
    I want to believe that it will be a good paper, I really do but I'm afraid edexcel is gunna pull another c3 on us :rolleyes: I mean, it is edexcel we're talking about...
    The more you consume the mind with negativity the less time you have to relax and get familiar with the things that could make the difference.
    Nobody knows what the paper will be like.
    Everybody knows what they can do to be in the best position they can be come 9am tomorrow morning.

    I think forums are great for sharing knowledge and study help but I don't believe any forum is ideal if the vibe is a defeatist one especialy the night before an exam.

    Heck it seems some people have already made their Hitler video on speculation alone.

    You can only do what you have prepped for. If you have put 100% effort in then nobody can ever say you didnt give it your best.
    If the paper is easy, if the paper is hard, if the paper is in the middle, one thing remains.....A positive student will do better on that paper than one that goes in with doubt.

    Good luck for tomorrow.
    Offline

    0
    ReputationRep:
    (Original post by justinawe)
    I'd use \cos 2A = 1 - 2\sin^2 A

    specifically in this case A=x/2, so:

    \cos x = 1 - 2\sin^2 \dfrac{x}{2}
    thnx but I don't understand why you use half angle isn't the question: \displaystyle \int \sqrt2 - 2cos^\frac{1}{2} x dx i'm really confused
    Offline

    0
    ReputationRep:
    (Original post by Lolc4)
    Thanks a bundle!
    Lol these are all in the formula book wtf


    Posted from TSR Mobile
    Offline

    15
    ReputationRep:
    (Original post by Myocardium)
    Yes, it'd be 3^xln(3)?
    Hence integrating 3^x leads to division by ln(3).
    Offline

    2
    ReputationRep:
    (Original post by Myocardium)
    How would you integrate something like 3^x?
    \int a^x = \frac{a^x} {\ln a} +C
    Offline

    0
    ReputationRep:
    (Original post by ACBLISS)
    can soomeone give me the shapes we need to know, i/e their formulas for C4
    Is it just cylinder,cone,sphere and maybe prism?
    http://4.bp.blogspot.com/-E7F2lQoZQy...600/volume.jpg
    Offline

    1
    ReputationRep:
    Name:  photo.jpg
Views: 178
Size:  512.7 KBName:  photo.jpg
Views: 178
Size:  512.7 KBName:  photo.jpg
Views: 178
Size:  512.7 KB


    can ANYONE please help me solve this equation to get it in terms of V, as I have put at the side can't do it at all
    Offline

    1
    ReputationRep:
    (Original post by orange94)
    I used substitution and got this , it's wrong!

    What did I do wrong ?? Help ??

    Name:  ImageUploadedByStudent Room1371490410.611607.jpg
Views: 91
Size:  114.0 KB


    Posted from TSR Mobile
    u forgot to find du/dx and sub that in
    Offline

    0
    ReputationRep:
    please guys i want help with the question 7 c) in the paper of January 2013...
    Offline

    0
    ReputationRep:
    (Original post by orange94)
    Lol these are all in the formula book wtf


    Posted from TSR Mobile
    Other than the ones which aren't in there, but you could easily rearrange them or learn them.
    Offline

    2
    ReputationRep:
    (Original post by jadecross)
    thnx but I don't understand why you use half angle isn't the question: \displaystyle \int \sqrt2 - 2cos^\frac{1}{2} x dx i'm really confused
    The half angle is because you have cos x
    So to be able to use the double angle formulae, x must be x/2
    so cos2(x/2) = cos x
    Offline

    3
    ReputationRep:
    (Original post by jadecross)
    thnx but I don't understand why you use half angle isn't the question: \displaystyle \int \sqrt2 - 2cos^\frac{1}{2} x dx i'm really confused
    You want to get rid of the square root, so you need it in terms of something squared.

    \sqrt{2 - 2\cos x}

    = \sqrt{2 - 2(1 - 2\sin^2 \frac{x}{2})}

    = \sqrt{2 -2 + 4\sin^2 \frac{x}{2}}

     = \sqrt{4\sin^2 \frac{x}{2}}

    = 2\sin \frac{x}{2}
    Offline

    15
    ReputationRep:
    (Original post by sonyeric33)
    u forgot to find du/dx and sub that in
    I thought this, but luckily du=dx in this case.
 
 
 
Poll
If you won £30,000, which of these would you spend it on?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.