\[\boxed{\mathbf{65}\mathbf{.}}\]
\[1)\ a - x = a^{1} - x^{1} = a^{\frac{3}{3}} - x^{\frac{3}{3}} =\]
\[= \left( a^{\frac{1}{3}} \right)^{3} - \left( x^{\frac{1}{3}} \right)^{3} =\]
\[= \left( a^{\frac{1}{3}} - x^{\frac{1}{3}} \right)\left( a^{\frac{2}{3}} + a^{\frac{1}{3}}x^{\frac{1}{3}} + x^{\frac{2}{3}} \right)\]
\[2)\ x^{\frac{3}{2}} - y^{\frac{3}{2}} = \left( x^{\frac{1}{2}} \right)^{3} - \left( y^{\frac{1}{2}} \right)^{3} =\]
\[= \left( x^{\frac{1}{2}} - y^{\frac{1}{2}} \right)\left( x + x^{\frac{1}{2}}y^{\frac{1}{2}} + y \right)\]
\[3)\ a^{\frac{1}{2}} - b^{\frac{1}{2}} = a^{\frac{3}{6}} - b^{\frac{3}{6}} =\]
\[= \left( a^{\frac{1}{6}} \right)^{3} - \left( b^{\frac{1}{6}} \right)^{3} =\]
\[= \left( a^{\frac{1}{6}} - b^{\frac{1}{6}} \right)\left( a^{\frac{1}{3}} + a^{\frac{1}{6}}b^{\frac{1}{6}} + b^{\frac{1}{3}} \right)\]
\[4)\ 27a + c^{\frac{1}{2}} = 3^{3}a^{\frac{3}{3}} + c^{\frac{3}{6}} =\]
\[= \left( 3a^{\frac{1}{3}} \right)^{3} + \left( c^{\frac{1}{6}} \right)^{3} =\]