User:Quietly/sandbox

Math with Tom
$$\frac{\sqrt{x}}{3\sqrt{x}-\sqrt{y}} = \frac{\sqrt{x}}{3\sqrt{x}-\sqrt{y}}\frac{(3\sqrt{x}-\sqrt{y})}{(3\sqrt{x}-\sqrt{y})}$$

$$(3\sqrt{x}-\sqrt{y})(3\sqrt{x}-\sqrt{y}) = 9x - 3\sqrt{xy} - 3\sqrt{xy} + y = 9x -6\sqrt{xy}+y$$ $$(3\sqrt{x}-\sqrt{y})(3\sqrt{x}+\sqrt{y}) = 9x - 3\sqrt{xy} + 3\sqrt{xy} + y = 9x+y$$