Why is this Maclaurin series incorrect?

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SUMMARY

The discussion centers on the derivation of the Maclaurin series for the function \( f(x) = x^2 e^x \). The correct approach involves recognizing that the exponential function can be expressed as a power series, specifically \( e^x = \sum_{n=0}^{\infty} \frac{x^n}{n!} \). By substituting this into the expression for \( x^2 e^x \), the series simplifies to \( \sum_{n=0}^{\infty} \frac{x^{n+2}}{n!} \), confirming that this is indeed a Maclaurin series, which is a Taylor series expanded at the point \( 0 \).

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tmt1
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I need to find the Maclaurin series for

$$f(x) = x^2e^x$$

I know

$$e^x = \sum_{n = 0}^{\infty} \frac{x^n}{n!}$$

So, why can't I do

$$x^2 e^x =x^2 \sum_{n = 0}^{\infty} \frac{x^n}{n!} = \sum_{n = 0}^{\infty} \frac{x^2 x^n}{n!} $$
 
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You can! I'd say you could combine the exponents in your final result:
$$x^2e^x=\sum_{n=0}^{\infty}\frac{x^{n+2}}{n!}.$$
Now this is a Maclaurin series, not a Taylor series expanded at a point other than $0$, right?
 

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