> (-2)^{3/2}=\sqrt{(-2)^3} = ...
This equation is wrong; see http://planetmath.org/encyclopedia/FractionPower.html, the paragraph 4.
> If $x$ is negative, $a$ is an integer, and $b$ is a positive integer with $\gcd(a,b)=1$, then $x^(a/b)$ is only real when $b$ is odd.
This is not true; e.g. (-1)^{1/3} is not well-defined (1/3 = 2/6).
Ah, the thing is so difficult to learn =o(
Cf. also "generalpower".
Jussi |
|
![[parent]](http://images.planetmath.org:8080/images/uparrow.png)