Using the laws of exponents, we can derive what fractional and
negative powers mean:
$\displaystyle{a^0=a^{1-1} = \frac{a^1}{a^1} = 1,}$ as
long as $a \ne 0$.
$\displaystyle{a^{-n}=a^{0-n}=\frac{a^0}{a^n} =
\frac{1}{a^n},}$ as long as $a \ne 0$.
$\displaystyle{\left(a^{p/q}\right)^q=a^p}$, so
$\displaystyle{a^{p/q}=\sqrt[q]{a^p}=\left(\sqrt[q]a\right)^p,}$
as long as $a\ge0$.
Notice: the expression
$0^0$, as well as negative powers of 0 are not
defined, and neither are fractional powers of
negative numbers, since if $a<0$, $a^p$ will not have a (real)
$q$-th root.
DO:
You must know all the exponential rules, so please review and
work on this and the previous slide if you have not totally
mastered these rules.