Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta
    Offline

    0
    ReputationRep:
    how do you work out the range and domain of a function
    it always comes up in c3
    its worth like 1 or 2 marks normally but i never get it :/
    Offline

    12
    ReputationRep:
    (Original post by maths-mental)
    how do you work out the range and domain of a function
    it always comes up in c3
    its worth like 1 or 2 marks normally but i never get it :/
    I always get confused with these yet in seems so simple.
    Well the domain is the values which x takes and the range is the y values.
    If you know the domain/range for a function e.g. f(x) then the domain/range of f-1(x) is just the opposite way round..i think.
    xxx
    • Thread Starter
    Offline

    9
    ReputationRep:
    Can someone show me the step-by-step differentiation of this:

    f(x)=3e^x - \dfrac{1}{2}lnx - 2

    Thanks!
    Offline

    2
    ReputationRep:
    I think its

    3xe^x- \frac{x}{2}lnx
    • Thread Starter
    Offline

    9
    ReputationRep:
    According to the markscheme, the answer is:

    3e^x - \dfrac{1}{2x}

    Dunno where the \dfrac{1}{2x} came from.
    Offline

    0
    ReputationRep:
    (Original post by Doughboy)
    According to the markscheme, the answer is:

    3e^x - \dfrac{1}{2x}

    Dunno where the \dfrac{1}{2x} came from.
    you take the derivative of x which is 1 than divide the derivative of the function by the function, and if there is a constant you just multiply.

    generally if you have a expression like this;  k ln (f(x))  than the derivative is

     k \times\frac{f'(x)}{f(x)}

    k is the constant. so they took the derivative of x, than divided it by x and the constant was 1/2 which they just left at the bottom, instead of leaving it multiplied by 1/2
    Offline

    2
    ReputationRep:
    Wait of course the derivative is 1/x not lnx :P
    • Thread Starter
    Offline

    9
    ReputationRep:
    Oh, wait. I was over-thinking this one!
    I just had to multiply -\dfrac{1}{2} by \dfrac{1}{x}
    Offline

    2
    ReputationRep:
    (Original post by unknownking321)
    can someone please help me. i'm looking for a song that has 'lalala' repeated in it and has lots of clapping. its quite catchy and sounds similar to something that the ting tings would release.
    Just a guess, it's not Brick By Boring Brick by Paramore is it?
    Offline

    0
    ReputationRep:
    over the past 2 or 3 weeks a new advert for sky HD has come up, it is pritty much the same as the last advert they had but with different music. I am trying to find out the name of the music or the person who created it. Tar
    Offline

    15
    ReputationRep:
    "Another Sky HD ad, this one promoting the £49 Sky+ HD box. The track is SRXT by Bloc Party, from the 2007 A Weekend In The City CD."
    Offline

    0
    ReputationRep:
    (Original post by SirRamAlot)
    "Another Sky HD ad, this one promoting the £49 Sky+ HD box. The track is SRXT by Bloc Party, from the 2007 A Weekend In The City CD."
    That's not the track, it's from a newer advert they have been airing recentlly
    Offline

    15
    ReputationRep:
    Ohh, I probably haven't seen it.
    Offline

    14
    ReputationRep:
    (Original post by SFsucks)
    over the past 2 or 3 weeks a new advert for sky HD has come up, it is pritty much the same as the last advert they had but with different music. I am trying to find out the name of the music or the person who created it. Tar
    what you about this song
    http://www.youtube.com/watch?v=mzMcNAe4nE8
    Offline

    15
    ReputationRep:
    (Original post by SFsucks)
    That's not the track, it's from a newer advert they have been airing recentlly
    Oh actually what about "The Yeah Yeah Yeahs - Runaway"?
    Offline

    13
    ReputationRep:
    U guys there is a question in the exam style paper in the Edexcel book page 140 in old book, question 6b.....can any one answers this for me .....(tanp=-2)
    i differentiated the equation

    The Question States:
    The Curve C has equation y=tanx + lnsecx (-pie/2<x<0)
    At point P on C, Whose X coordinate is P, The gradient is 3

    B) Show that tanp=-2


    thanks
    Online

    16
    ReputationRep:
    (Original post by MadMaths)
    U guys there is a question in the exam style paper in the Edexcel book page 140 in old book, question 6b.....can any one answers this for me .....(tanp=-2)
    i differentiated the equation

    The Question States:
    The Curve C has equation y=tanx + lnsecx (-pie/2<x<0)
    At point P on C, Whose X coordinate is P, The gradient is 3

    B) Show that tanp=-2


    thanks
    At the point P, dy/dx = 3, so make your differntiated equation equal to 3, and sub in x =p , into it and simplify, rearrange to get tanp=-2.
    Offline

    14
    ReputationRep:
    (Original post by FOBfan_xxo)
    Am just guessing here... backstreet boys - bigger? :confused:
    lol thanks for trying but no
    Offline

    2
    ReputationRep:
    i'm also doing this paper.
    has anyone done any Solomon's? is it worth it?
    Offline

    2
    ReputationRep:
    I just did the Jun 09 paper, it's quite easy!

    edit: there used to be a question here, but it was stupid, and I got the answer.
 
 
 
Turn on thread page Beta
Updated: June 14, 2010
Poll
Do I go to The Streets tomorrow night?

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

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