Помогите сократить дроби!))

Благодарю ;)

y^2-3y-4=(y-3)(y+1) y^2-1=(y-1)(y+1)((y-3)(y+1))/((y-1)(y+1))=(y-3)/(y-1)x^2-5x+4=(x-4)(x-1)x^2-16=(x-4)(x+4)((x-4)(x+4))/((x-4)(x-1))=(x+4)/(x-1)***************************************