Question

Решите эти два примера в колледже задали, а я не черта не помню с 9

Answer 1

$(\frac{4x}{ x^{2} - y^{2} } - \frac{4x-4y}{ x^{2} - y^{2} }) : \frac{y}{x-y} =- \frac{4y}{ x^{2} - y^{2} } * \frac{x-y}{4} =- \frac{4}{x-y}$ 

$(\frac{3 b^{2}+2b }{ b^{2}-4 } - \frac{b}{b-2} )= \frac{ 2b^{2} }{ b^{2}-4} * \frac{b+2}{2b} = \frac{b}{b-2}$

Answer 2

$( \frac{4x}{x^2-y^2} - \frac{4}{x+y}) / \frac{y}{x-y} =( \frac{4x}{(x-y)(x+y)} - \frac{4}{x+y}) / \frac{y}{x-y} = \\ = \frac{4x - 4x+4y}{x^2-y^2} / \frac{y}{x-y} = \frac{4y}{x^2-y^2} * \frac{x-y}{y} = \frac{4}{x+y}$

$( \frac{3b^2+2b}{b^2-4} - \frac{b}{b-2} )/ \frac{2b}{b+2} = \frac{3b^2+2b-b(b+2)}{b^2-4} * \frac{b+2}{2b} = \frac{3b^2+2b-b^2-2b}{b^2-4} * \frac{b+2}{2b} = \\ \\ = \frac{2b^2}{b^2-4} * \frac{b+2}{2b} = \frac{2}{b-2}$