[(a+2)分之(a^-5a+2)+1]÷(a^2+4a+4)分之(a^2-4),其中a=2+根号3.

[(a^2-5a+2)/(a+2)+1]÷(a^2-4)/(a^2+4a+4)
=[(a^2-5a+2+a+2)/(a+2)][(a^2+4a+4)/(a^2-4)]
=[(a-2)^2/(a+2)])][(a+2)^2/(a-2)(a+2)]
=(a-2)^2(a+2)^2/(a+2)^2(a-2)
=a-2
=2+√3-2
=√3