Simplify the expression using exponent rules.
$(-5a^2)\left(3a^8\right)$

Simplify the expression using exponent rules.

$-\frac{12b^{11}}{4b^7}$

Rewrite the expression using exponent rules.

${\left(4x^2\right)}^3$

Rewrite the expression using exponent rules.

${\left(\frac{3x^4}{y^{-2}}\right)}^3$