Answer
(a) $(2x+1)\sqrt {2x}$
(b) $(3x^2-2x)\sqrt {2x}$
Work Step by Step
(a) $\sqrt {8x^3}+\sqrt {2x}=\sqrt {2^2(2)x^2x}+\sqrt {2x}=2x\sqrt {2x}+\sqrt {2x}=(2x+1)\sqrt {2x}$
(b) $\sqrt {18x^5}-\sqrt {8x^3}=\sqrt {3^2(2)(x^2)^2x}-\sqrt {2^2(2)x^2x}=3x^2\sqrt {2x}-2x\sqrt {2x}=(3x^2-2x)\sqrt {2x}$