Calculating Taylor Series for e^(x^2) around x=0

dantheman57
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Homework Statement


Find the Taylor series of e^(x^2) about x=0


Homework Equations



Taylor Series = f(a) +f'(a)(x-a) + (f''(a)(x-a)^2)/2 ...

The Attempt at a Solution



So, the first term is pretty obvious. It's e^0^2, which is zero.

The second term is what got me. (e^x^2)'=2x*(e^x^2), so at zero that is zero. Multiply by x, still zero. But the answer key says the second term is x^2. I really cannot understand this.

Thanks!
 
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dantheman57 said:
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So, the first term is pretty obvious. It's e^0^2, which is zero.

My bad. e^0^2 is one. Typo.
 
Keep going. It's the f'' term that is the second term.
 
Thank you so much!
 
You can also take the Taylor series of ex and then just fill in x2.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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