(x^2y-4^y3^/x^2+4xy+4y^2)·(4xy/x-2y+x),其中x=根号2-1,y=根号2+1
=(x²y-4y³)/(x+2y)²*(4xy+x²-2xy)/(x-2y)
=y(x+2y)(x-2y)/(x+2y)²*x(x+2y)/(x-2y)
=xy
=(√2-1)(√2+1)
=2-1
=1