Answer
$\frac{1}{x^9}$
Work Step by Step
$x^3\cdot x^{-12}$
Recall the power rule: $a^{m}\cdot a^{n} = a^{mn}$
Thus,
$x^3\cdot x^{-12}$ = $x^{3-12}$
$=x^{-9}$
Recall the negative exponent rule: $=a^{-n} = \frac{1}{a^n}$
Hence,
$x^{-9} = \frac{1}{x^9}$
