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$y = 1 + \frac{x}{1!} + \frac{x^2}{2!} + ..... + \frac{x^n}{n!} $

We needed to find to derivative of this function.

I just wrote the given series is the Taylor expansion of $e^x$, therefore $f(x)$ and $f'(x)$ are the same, but the correct answer is $y-\frac{x^n}{n!}$.

Can anybody tell me where I went wrong?

I mean what's wrong in my method?

I am not asking for the solution of this problem.

Bernard
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B Luthra
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    The Taylor expansion of $e^x$ is an infinite series, whereas the function above is a finite series. – NickD Nov 01 '19 at 12:31

1 Answers1

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You have written a finite series approximation of $e^x$, not the full expansion. If you wrote the full expansion, it would differentiate to itself, but this finite series does not.

John Doe
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