## Elementary Algebra

$30a$
Using the properties of radicals, the given expression, $(5\sqrt[]{a})(6\sqrt[]{a}) ,$ simplifies to \begin{array}{l} 5(6)\sqrt[]{a(a)} \\\\= 30\sqrt[]{(a)^2} \\\\= 30a .\end{array} Note that all variables represent positive real numbers.