是a+b=根号下5+2倍根号6吧,要不算不出来
(a+b)(a-b)=a^2-b^2=√(5+2√6)*√(5-2√6)=√(25-24)=1
a^2=b^2+1
[(a^2-2)/(b^2-1)]^2008=(-1)^2008=1