(a^2-b^2)/(a^2b+ab^2)/[1-(a^2+b^2)/2ab]
=(a-b)(a+b)/[ab(a+b)]/[(2ab-a^2-b^2)/2ab]
=(a-b)/ab/[-(a-b)^2/2ab]
=-2/(a-b)
=-2/(2+√3-2+√3)
=-√3/3
(a^2-b^2)/(a^2b+ab^2)/[1-(a^2+b^2)/2ab]
=(a-b)(a+b)/[ab(a+b)]/[(2ab-a^2-b^2)/2ab]
=(a-b)/ab/[-(a-b)^2/2ab]
=-2/(a-b)
=-2/(2+√3-2+√3)
=-√3/3