#### Answer

$\frac{3\sqrt 2}{4x}$

#### Work Step by Step

$\sqrt \frac{8}{x^{2}}-\sqrt \frac{50}{16x^{2}}$
=$\frac{\sqrt 8}{\sqrt {x^{2}}}-\frac{\sqrt {50}}{\sqrt {16x^{2}}}$
=$\frac{\sqrt {4\times2}}{\sqrt {x^{2}}}-\frac{\sqrt {2\times25}}{\sqrt {16x^{2}}}$
=$\frac{2\sqrt {2}}{x}-\frac{5\sqrt {2}}{4x}$
=$\frac{4(2\sqrt {2})-5\sqrt 2}{4x}$
=$\frac{8\sqrt {2}-5\sqrt 2}{4x}$
=$\frac{3\sqrt 2}{4x}$