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Edexcel A Level Maths Differentiation HELP (Exponentials) watch

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    Hi,
    Please could someone help me with this question? I have attatched as far as I have gotten but I am having trouble proving (b) so some advice to go next would be really appreciated.

    Many thanks.
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    My workings:
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    (Original post by aliasanoynmous)
    Hi,
    Please could someone help me with this question? I have attatched as far as I have gotten but I am having trouble proving (b) so some advice to go next would be really appreciated.

    Many thanks.
    My workings:
    You're nearly there. You can divide by x (do you know why you're allowed to?) and then multiply everything by 2. Rearrangement grants the answer.
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    (Original post by RDKGames)
    You're nearly there. You can divide by x (do you know why you're allowed to?) and then multiply everything by 2. Rearrangement grants the answer.
    Brilliant! I did what you said and I got the answer easily. But, as you said, I do not know why i'm allowed to do this so please could you explain? It would really help my understanding. Thank you.
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    (Original post by aliasanoynmous)
    Brilliant! I did what you said and I got the answer easily. But, as you said, I do not know why i'm allowed to do this so please could you explain? It would really help my understanding. Thank you.
    You know, from the diagram, that the x-coordinate of P cannot be 0. If it would be 0, then you'd just end up at the origin again, which isn't the point of interest. Since x \neq 0 for P, you can freely divide by it as needed.
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    (Original post by RDKGames)
    You know, from the diagram, that the x-coordinate of P cannot be 0. If it would be 0, then you'd just end up at the origin again, which isn't the point of interest. Since x \neq 0 for P, you can freely divide by it as needed.
    Ok thank you. Yes I understand this.
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    (x^3-2x) e^-x= 1/2 xx(x^2- 2) e^-x= 1/2 x If x is not equal to 0 ( (0,0) is one of two intersecting points.)(x^2- 2) e^-x= 1/2 (x^2- 2) /e^x= 1/22(x^2- 2) = e^x2x^2- 4= e^x2x^2= e^x 4
 
 
 
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