## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$(6x-1)\sqrt[]{x}$
Simplifying each term and then combining like terms, the given expression, $2\sqrt[]{9x^3}-\sqrt[]{x} ,$ is equivalent to \begin{array}{l}\require{cancel} 2\sqrt[]{9x^2\cdot x}-\sqrt[]{x} \\\\= 2\sqrt[]{(3x)^2\cdot x}-\sqrt[]{x} \\\\= 2\cdot3x\sqrt[]{x}-\sqrt[]{x} \\\\= 6x\sqrt[]{x}-\sqrt[]{x} \\\\= (6x-1)\sqrt[]{x} .\end{array} * Note that it is assumed that all variables represent positive numbers.