7/8 класс, алгебра. 121 (в,е)

(x-x^2+y^2/x+y)=xy+y^2/x+y (1/y+2/x-y)=x-y+2/xy-y^2 xy+y^2/x+y*x-y+2/xy-y^2=2

№ 121 в) [latex] (x-\frac{x^2+y^2}{x+y} )*( \frac{1}{y}+ \frac{2}{x-y} )= \frac{x^2+xy-x^2-y^2}{x+y} * \frac{x-y+2y}{y(x-y)} = \frac{xy-y^2}{x+y}* \frac{x+y}{y(x-y)} = [/latex] [latex]=\frac{xy-y^2}{y(x-y)}= \frac{y(x-y)}{y(x-y)} =1[/latex] е) [latex](b+1- \frac{1}{1-b}):(b- \frac{b^2}{b-1})= \frac{1-b^2-1}{1-b} : \frac{b^2-b-b^2}{b-1}= \frac{-b^2}{1-b}: \frac{-b}{b-1} = \frac{-b^2}{1-b}* \frac{b-1}{-b} = [/latex][latex]=\frac{b^2}{b-1}* \frac{b-1}{-b}= \frac{b^2}{-b}=-b [/latex]