- #1

- 241

- 0

[tex]

sinx=\sum_{n=0}^{\infty}(-1)^n\frac{x^{2n+1}}{(2n+1)!}

[/tex]

[tex]

\frac{d}{dx}(sinx)=cosx=\sum_{n=1}^{\infty}(-1)^n(2n+1)\frac{x^{2n}}{(2n+1)!}

[/tex]

it seems as if it wouldnt be

[tex]

cosx=\sum_{n=0}^{\infty}(-1)^n\frac{x^{2n}}{(2n)!}

[/tex]