[(x²-3x-6)/(x+2)-1]÷(x²-4)/(x²+4x+4)
=(x²-3x-6-x-2)/(x+2)×(x²+4x+4)/[(x+2)(x-2)]
=(x²-4x-8)/(x+2)×(x+2)²/[(x+2)(x-2)]
=[(x-2)²-12]/(x-2)
=x-2-12/(x-2)