（3-x分之x-1）平方÷（x平方-6x+9分之9-x平方）平方*x平方-2x+1分之6+2x
=[(x-1)/(3-x)]²÷[(9-x²)/(x²-6x+9)]²*[(6+2x)/(x²-2x+1)]
=[(x-1)/(3-x)]²÷[(x²-6x+9)/(9-x²)/]²*[(6+2x)/(x²-2x+1)]
=[(x-1)/(3-x)]²*[(x-3)²/(x+3)(3-x)]²*[2(3+x)/(x-1)²]
=[(x-1)²/(3-x)²]*[(x-3)^4/(x+3)²(3-x)²]*[2(3+x)/(x-1)²]
={1/(x+3)]*[2]
=2/(x+3)