X2+4x-3/X4-5X2+4 what is the domain of this function

Domain is the value of x

the demonimator cannot be zero

factor the denominator: (x^2-1) (x^2-4) ≠0

factor again: (x+1) (x-1) (x+2) (x-2) ≠0

x≠1,-1,2,-2

the domain is all real number except 1,-1,2,-2