Answer:
[tex]f(x)= x-6\\g(x) = x^\frac{1}{2} (x+3)\\\left(x-6\right)\left(x^{\frac{1}{2}}\left(x+3\right)\right):\quad x^{\frac{5}{2}}-3x^{\frac{3}{2}}-18x^{\frac{1}{2}}\\x^2\sqrt{x}-3x\sqrt{x}-18x^{\frac{1}{2}}\\[/tex]
Factor and you get
[tex]x^\frac{1}{2} (x-6)(x+3)[/tex]
Hope this helps!!!