Пожалуйста сделайте умоляю №290 надеюсь вы поможете Упростите выражение. ДАЮ 34 БАЛЛА...

$1. \frac{4}{a+2} - \frac{3}{a-2} + \frac{12}{ a^{2}-4} = \\ \\= \frac{4(a-2)-3(a+2)+12}{ a^{2}-4 } = \\ \\ = \frac{4a-8-3a-6+12}{ a^{2}-4 } = \\ \\ =\frac{a-2}{a^{2}-4} = \frac{a-2}{(a-2)(a+2)} = \frac{1}{a+2} \\ \\ \\ 2. \frac{6m}{m-3} + \frac{ m^{2}+m }{4} * \frac{8}{m+1} = \\ \\ =\frac{6m}{m-3} + \frac{ m(m+1) }{4} * \frac{8}{m+1}= \\ \\ =\frac{6m}{m-3}+2m= \frac{6m+2m(m-3)}{m-3} =[tex] \\ \\ = \frac{6m+2 m^{2}-6m }{m-3} = \frac{2 m^{2} }{m-3}$ $\\ \\ \\$ 3. ( \frac{x}{x-y} - \frac{x}{x+y} ): \frac{xy}{x+y} = \\ \\ [/tex] $\\ \\ =\frac{x(x+y)-x(x-y)}{ (x-y)(x+y)} * \frac{x+y}{xy} = \\ \\ = \frac{ x^{2} +xy- x^{2} +xy}{x-y} * \frac{1}{xy} = \\ \\ = \frac{2xy}{(x-y)xy} = \frac{2}{x-y} \\ \\ \\ 4. \frac{y}{2x+2y} + \frac{x}{a-1} * \frac{a-1}{2x+2y} = \\ \\ = \frac{y}{2x+2y}+ \frac{x}{2x+2y} = \\ \\ = \frac{x+y}{2(x+y)} = \frac{1}{2}$