x²-4x-5 / x²y-y
x²-4x-5=0
D=b²-4ac=16+20=36
x1= -b+√D / 2a= 4+6 /2= 5
x2= -b-√D / 2a= 4-6 / 2= -1
x²-4x-5=(x+1)(x-5)
(x+1)(x-5) / y(x²-1) = (x+1)(x-5) / y(x+1)(x-1)= x-5 / y(x-1)
