lg(x+y)+lg(2x+3y)=lg12+lgx+lgy
lg[(x+y)(2x+3y)]=lg(12xy)
(x+y)(2x+3y)=12xy
2x^2+5xy+3y^2=12xy=0
2x^2-7xy+3y^2=0
(2x-y)(x-3y)=0
2x=y或x=3y
x/y=1/2或x/y=3纠正2x^2+5xy+3y^2-12xy=0谢谢