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

    0
    ReputationRep:
    (Original post by Theafricanlegend)
    why isnt it 3^-xln-3?
    y = -3 ^ (-x)
    ln y = - ln 3 ^-x
    ln y = x ln 3
    1/y dy/dx = ln 3
    dy/dx = (-3 ^ (-x) * ln 3)

    although it should be positive ....
    Offline

    0
    ReputationRep:
    How do you find the coords minimum/maximum of a curve? I know you differentiate and equate to 0, but how do you find one if there is a both a minimum and a maximum? If I remember correctly, it should come out with two results, and the negative one is the x coord of the maximum?
    Offline

    2
    ReputationRep:
    (Original post by Rayquaza)
    Still stuck :/
    expand the brackets and if you sub it back into the original equation what do you get? it should be pretty straightforward now..
    • TSR Support Team
    • Community Assistant
    • PS Reviewer
    Offline

    18
    ReputationRep:
    (Original post by zzz.)
    alot of people are saying the c4 paper is gnna be worse than the C3 ppr!!!


    But your comment made me happy.. What makes you think that though??
    I doubt the paper would be that hard, remember Edexcel would have listened to the recent criticism from the C3 paper.

    It depends on when the C4 papers were delivered to the schools. If they were delivered a couple of days after the c3 exam, then it wouldn't be such a hard paper!

    Remember to stay positive and do your best! That's the only thing you can do :yy:
    Offline

    0
    ReputationRep:
    (Original post by kuku2013)
    hey thanks, I don't understand from the 5th step!! why do you have to make it all into ln(2)?
    I turned it into ln2, so that I can factorise it out.
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by ACBLISS)
    integration
    Okay well I'd use the substitution of U = X^2 and that should then equate it down rather nicely
    Offline

    15
    ReputationRep:
    integrate 1/sin^2xcos^2x please help
    Offline

    0
    ReputationRep:
    Going to head off now. Good luck for tomorrow everyone!
    Offline

    0
    ReputationRep:
    (Original post by MathsNerd1)
    Just remain calm as if you've covered everything then that's all you can do, now getting a good nights rest before the exam would be very advisable by myself as you'll be both physically and mentally prepared
    Thanks
    Offline

    0
    ReputationRep:
    Can anyone confirm if we have to integrate x/1+x . = x-ln(x+1) ?
    Offline

    0
    ReputationRep:
    (Original post by Kreayshawn)
    can someone tell me what shapes we need to know the area/volume of?
    i've asked a few times but no response, don't wanna have to skip a whole question on the exam because i don't know the area/volume of something basic
    This is largely off the top of my head, somebody correct me if I've missed anything. As you can see, most of them are very simple. The only tricky ones, I think, would be the volume of a cone (1/3 * base * height), and area of a regular shape (which will almost definitely not come up).

    2D areas
    • Circle/semicircle
    • Rectangle
    • Triangle
    • Any regular shape (although they would have to give you a hint)


    3D volumes
    • Sphere/hemisphere
    • Cuboid
    • Cone (for any base)
    • Prism (cylinder is the most likely one to be asked for)


    3D surface areas
    • Cuboid
    • Err...


    You are given these by the formulae booklet (in the C1 section)
    • Surface area of a sphere
    • Surface area of a cone
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by Story)
    Can anyone confirm if we have to integrate x/1+x . = x-ln(x+1)
    This is what I got
    Offline

    2
    ReputationRep:
    (Original post by Theafricanlegend)
    integrate 1/sin^2xcos^2x please help
    hint: sin^2xcos^2x =( \frac{1}{2}sin2x )^2..
    Offline

    2
    ReputationRep:
    Is it just me or is June 12 really nice? Please please c4 paper, be like that D:
    Offline

    2
    ReputationRep:
    (Original post by MathsNerd1)
    Only on the questions that ask you to use substitution but I'm saying that I'll use the technique when trying to integrate the ones that can be done by recognition so I need to work out a suitable substitution first
    Ohh I see why not just do the integration by recognition? or do you mean to check your answer?
    I think you can do it on the graphical calculators I remember doing c2 integration and differentation, but it takes abit of time - is good to check your answer though.
    Offline

    0
    ReputationRep:
    (Original post by Jullith)
    Going to head off now. Good luck for tomorrow everyone!
    thanks for your help!!
    Offline

    0
    ReputationRep:
    Is there a way of knowing how to separate variables in differential equations?
    Offline

    3
    ReputationRep:
    (Original post by ACBLISS)
    oops the first one
    pfft, easy one then

    Spoiler:
    Show

    \dfrac{d}{dx}(e^{x^2}) = 2xe^{x^2}


    \displaystyle \int x^3e^{x^2} \ dx

     = \displaystyle \frac{1}{2} \int x^2 \cdot 2xe^{x^2} \ dx

     = \displaystyle \frac{1}{2} \left( x^2e^{x^2} - \int 2xe^{x^2} \ dx \right)

    =  \dfrac{1}{2} ( x^2e^{x^2} - e^{x^2}) + C

    = \dfrac{1}{2} e^{x^2} ( x^2 - 1) + C

    Offline

    0
    ReputationRep:
    integrate Sin(2X)Cos(2x) please help
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by justinawe)
    pfft, easy one then

    Spoiler:
    Show

    \dfrac{d}{dx}(e^{x^2}) = 2xe^{x^2}


    \displaystyle \int x^3e^{x^2} \ dx

     = \displaystyle \frac{1}{2} \int x^2 \cdot 2xe^{x^2} \ dx

     = \displaystyle \frac{1}{2} \left( x^2e^{x^2} - \int 2xe^{x^2} \ dx \right)

    =  \dfrac{1}{2} ( x^2e^{x^2} - e^{x^2}) + C

    = \dfrac{1}{2} e^{x^2} ( x^2 - 1) + C

    I got this via a substitution then by parts, that's the type of thing I'd like to appear tomorrow where you've got multiple steps to it
 
 
 
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.