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    just working through past papers for thursdays exam and i came across this:

    curve y = (4rtx)/(e^x)

    sorry bout lack of latex

    what does y = when x = 2???

    thats not the question obviously but everytime i type it in to, 2 seperate calculators i get 0.77
    the markscheme gets 1.083
    grr!
    any help would be much appreciated im hoping its a dodgy markscheme!
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    Try at least 4 calculators next time before bothering to post up a question like this...
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    (Original post by Door)
    Try at least 4 calculators next time before bothering to post up a question like this...
    do i take that as a sign that my calculators are failing me or is that you just being a troll!
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    troll
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    someone answer me properly pretty please
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    ummm are the "rt" unknown variables in the top line of the fraction??
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    I think he means square root 2 for that bit.

    I dont have a calculator.
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    basically e^2 is about 7.4
    4 x r x t x2 = 8rt
    8/7.4 = 1.08
    thus the answer is 1.08rt
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    (Original post by Door)
    4 rt 2 = 8
    thus 8 / 7.4 = 1.08..
    4 root 2 doesn't equal 8.

    I get 0.766, assuming the OP means \dfrac{4\sqrt{x}}{e^x}.
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     4 \sqrt2 = \sqrt32 It doesn't help one iota writing it this way!
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    (Original post by silent ninja)
     4 \sqrt2 = \sqrt32 It doesn't help one iota writing it this way!
    i dnt get it...who wrote it in that way?
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    You wrote something, we cant figure it out:

    (Original post by Door)
    basically e^2 is about 7.4
    4 x r x t x2 = 8rt
    8/7.4 = 1.08
    thus the answer is 1.08rt
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    ohh rite..
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    (Original post by silent ninja)
    You wrote something, we cant figure it out:

    that was wen i thought "rt" were unknown variables...
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    The confusion is arising because of the 'rt' bit.

    If y = (4(2)^(1/2))/e^2, then y = 0.77..

    If y = (4rt2)/e^2, where r and t are independent variables or 'rt' is a variable, then y = 1.083rt as in the markscheme.
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    (Original post by Door)
    that was wen i thought "rt" were unknown variables...
    Oh okay.

    Latex helps. It's not that hard to use, especially for simple functions like this.
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    The mark scheme is wrong, I have just done this question and got the Integral of \mathsrm{y = 4x^\frac{1}{2}e^{-x}} to be exactly 2.332 (using 3dp throughout), the mark scheme has 2.41 because it got f(2) = 1.083 for some bizarre reason!

    EDIT: Its because they have discounted the power of \frac{1}{2} for no reason, they have just forgotten it in the calculation, they have just done y = 4(2)e^{-2} - its just an error.
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    hey guys thanks for all the replies ye it is root 2!
    im gonna learn latex after my exams, im sure it will be helpful and i'v briefly glanced over it so i know its not hard!
    thanku triggerishappy for telling me its a dodgy markscheme!
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    Hi everyone i was just doing this question and thinking whaaaaaat
    Thanks =)
    Stupid markscheme x
 
 
 
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