x/2-y/3=0x/2=y/3x=2y/3(7x²-y²)/(x²-2xy+3y²)= （7*4y²/9-y²)/(4y²/9-2*2y/3*y+3y²)=（19y²/9）/（19y²/9）=1【数学辅导团】为您解答,如果本题有什么不明白可以...