化简:a^2-2a/a-a-3/1÷a^2-9/a-2,其中a=1

Question

化简:a^2-2a/a - a-3/1 ÷ a^2-9/a-2,其中a=1

Answer 1

原式=a/[a(a-2)]-1/(a-3)×(a+3)(a-3)/(a-2)
=1/(a-2)-(a+3)/(a-2)
=(1-a-3)/(a-2)
=-(a+2)/(a-2)
a=1
原式=-3/（-1）=3