Question

Помогите пж один пример)

Answer 1

$\tt (y+(y-1):(y+1))(y-(y+1):(y-1))=\bigg(y+\dfrac{y-1}{y+1}\bigg)\bigg(y-\dfrac{y+1}{y-1}\bigg)=\\ \\ =\dfrac{y^2+y+y-1}{y+1}\cdot\dfrac{y^2-y-y-1}{y-1}=\dfrac{y^2+2y-1}{y+1}\cdot\dfrac{y^2-2y-1}{y-1}=\\ \\ \\ =\dfrac{(y^2+2y-1)(y^2-2y-1)}{y^2-1}$