已知│x-3y-1│+(x+y)^2=4xy,求x/y的值
=>│x-3y-1│+x^2+2xy+y^2-4xy=0
=>│x-3y-1│+(x-y)^2=0
=>x-3y=1;x=y=>x=-1/2 ;y=-1/2
=> x/y =1