Binomial Theorem/Approximations/1st Order

Theorem

Consider the General Binomial Theorem:

$\paren {1 + x}^\alpha = 1 + \alpha x + \dfrac {\alpha \paren {\alpha - 1} } {2!} x^2 + \dfrac {\alpha \paren {\alpha - 1} \paren {\alpha - 2} } {3!} x^3 + \cdots$


When $x$ is sufficiently small that $x^2$ can be neglected then:

$\paren {1 + x}^\alpha \approx 1 + \alpha x$

and the error is of the order of $\dfrac {\alpha \paren {\alpha - 1} } 2 x^2$


Proof


This theorem requires a proof.
In particular: Not sure how this is formulated yet, I need a more precise definition and source work
You can help $\mathsf{Pr} \infty \mathsf{fWiki}$ by crafting such a proof.
To discuss this page in more detail, feel free to use the talk page.
When this work has been completed, you may remove this instance of {{ProofWanted}} from the code.
If you would welcome a second opinion as to whether your work is correct, add a call to {{Proofread}} the page.



Sources

  • 1953: L. Harwood Clarke: A Note Book in Pure Mathematics ... (previous) ... (next): $\text I$. Algebra: The Binomial Theorem: Approximations