- #1
Hernaner28
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Homework Statement
Prove that [tex]({x^n})' = n{x^{n - 1}}[/tex] by COMPLETE induction.
Homework Equations
Nothing.
The Attempt at a Solution
I did the base step for n=1 and then I suppctosed that it was true for n-1 but then I thought about it and I wonder why the professor told us to prove this by induction when in fact induction is useful for natural numbers, and that is true for real numbers.
Anyway, I think he asked for it because we know that:
$$\begin{align}
& x\text{ is differentiable}\Rightarrow xx={{x}^{2}}\text{ is dif}\text{.}\Rightarrow {{x}^{2}}x={{x}^{3}}\Rightarrow ...{{x}^{n}}\text{ is differentiable if }n\in \mathbb{N} \\
& c\in \mathbb{R}\Rightarrow c\cdot {{x}^{n}}\text{ is dif}\text{.}\Rightarrow P(x)={{a}_{0}}{{x}^{n}}+{{a}_{1}}{{x}^{n-1}}+...+{{a}_{n}}\text{ is differentiable} \\
\end{align}$$
So therefore we could finally prove at the same time that any polynomial is differentiable. But what to do on n-1? Just an idea please!
Thank you!
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