若x/y=2/3,求3x方+5xy-2y方/x方-3xy-10y方的值
问题描述：
若x/y=2/3,求3x方+5xy-2y方/x方-3xy-10y方的值
答
x/y=2/3∴x=2/3y把 x=2/3y代入3x方+5xy-2y方/x方-3xy-10y方得原式=(4y²/3+10y²/3-2y²)/(4y²/9-2y²-10y²)=(8y²/3)/(-104y²/9)=-3/13