Evaluate: 9x^2-12x

Expression: $9x^{2}-12x$

Apply exponent rule $a^{b+c}=a^{b}a^{c}$

$=9xx-12x$

Rewrite $9$ as $3\cdot 3$

$=3\cdot 3xx-3\cdot 4x$

Factor out common term $3x$

$=3x(3x-4)$