Ответ:

Объяснение:

[tex]a) (\frac{9y(x+y) - 9xy}{x(x+y)} )* \frac{(x+y)^{2} }{27y^{3} } \\= \frac{9xy + 9y^{2} - 9xy}{x(x+y)} * \frac{(x+y)^{2} }{27y^{3} } \\= \frac{9y^{2} }{x(x+y)} * \frac{(x+y)^{2} }{27y^{3} }\\ = \frac{x+y}{3xy}[/tex]

[tex]b) (\frac{4x(x-2)-12x}{x-2} ): \frac{x(x-2)-8x+25}{x-2}\\ = \frac{4x^{2} - 8x -12x }{x-2} * \frac{x-2}{x^{2} -2x - 8x+25}\\ = \frac{4x^{2} - 20x}{x-2} * \frac{x-2}{x^{2} -10x+25}\\ = \frac{4x(x-5)}{x^{2} -10x+25} \\= \frac{4x(x-5)}{(x-5)^{2} } \\= \frac{4x}{x-5}[/tex]