[(x-4)/(x^2-1)]÷[(x^2-3x-4)/(x^2+2x+1)]+1/(x-1)
=[(x-4)/(x+1)(x-1)]÷[(x-4)(x+1)/(x+1)^2]+1/(x-1)
=[(x-4)/(x+1)(x-1)]÷[(x-4)/(x+1)]+1/(x-1)
=(x-4)(x+1)/[(x+1)(x-1)(x-4)]+1/(x-1)
=1/(x-1)+1/(x-1)
=2/(x-1)
=2/(2√3+1-1)
=2/(2√3)
=1/√3
=√3/3