√5是最简根式所以3a=5a=5/3
(x+2y)(x-y)=0x=-2y或x=yx=-2y原式=(4y²-6y²+y²)/(4y²+y²)=-y²/5y²=-1/5x=y原式=(y²+3y²+y²)/(y²+y²)=5y²/2y²=5/2所以原式=-1/5或5/2
