解ï¼
x²+xy-2y²=0
(x-y)(x+2y)=0
x-y=0æx+2y=0
x=yæx=-2y
äºæ¯
ï¼1ï¼x=yæ¶ï¼
(x²+3xy+y²)/(x²+y²)
=(y²+3y²+y²)/(y²+y²)
=5y²/2y²
=5/2 ï¼2åä¹5ï¼
ï¼2ï¼x=-2yæ¶ï¼
(x²+3xy+y²)/(x²+y²)
=(4y²-6y²+y²)/(4y²+y²)
=-y²/5y²
=-1/5 ï¼-5åä¹1ï¼
å¾çæ ¼å¼