x-y/x+3÷x²-y²/x²+6xy-2y/x+y
解：原式=x-y/x+3y×（x-3y)²/(x-y)(x+y)-2y/x+y
=x+3y/x+y-2y/x+y
=x+3y-2y/x+y
=x+y/x+y
=1
高昌宁
高昌宁