先化简再求值,（1）x²+2x+1/x²-1（2）3a²-ab/9a²-6ab+

(x²+2x+1)/(x²-1)
=(x+1)²/[(x+1)(x-1)]
=(x+1)/(x-1)
(3a²-ab)/(9a²-6ab+b²)
=a(3a-b)/(3a-b)²
=a/(3a-b)
=-8/(-8×3-2)
=-8/(-26)
=4/13