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# Edexcel A Level Maths Differentiation HELP (Exponentials) watch

1. 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:
Attachment 702956702958
Attached Images

2. (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 (do you know why you're allowed to?) and then multiply everything by 2. Rearrangement grants the answer.
3. (Original post by RDKGames)
You're nearly there. You can divide by (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.
4. (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 for P, you can freely divide by it as needed.
5. (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 for P, you can freely divide by it as needed.
Ok thank you. Yes I understand this.
6. (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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