Question

(a2-1)/(a-1)-(a-1)/a2-a,其中a=2-√3（先化简,再求值,要化简到最简分数）

Answer 1

(a²-1)/(a-1)-(a-1)/(a²-a)

=(a-1)(a+1)/(a-1)-(a-1)/a(a-1)

=a+1-1/a

a=2-√3时,原式=2-√3+1-1/(2-√3)=3-√3-(2+√3)/(4-3)=3-√3-2-√3=1-2√3