Question

7/8 класс, алгебра. 121 (в,е)

Answer 1

(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

Answer 2

№ 121

в)
$(x-frac{x^2+y^2}{x+y} )*( frac{1}{y}+ frac{2}{x-y} )= frac{x^2+xy-x^2-y^2}{x+y} * frac{x-y+2y}{y(x-y)} = frac{xy-y^2}{x+y}* frac{x+y}{y(x-y)} =$ $=frac{xy-y^2}{y(x-y)}= frac{y(x-y)}{y(x-y)} =1$

е)
$(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} =$$=frac{b^2}{b-1}* frac{b-1}{-b}= frac{b^2}{-b}=-b$