已知2x2-3xy+y2=0,若xy不等于0,则x/y+y/x的值是?A:2或2/5 b:2 c:5/2 d:-2或-5
3个回答
2x²-3xy+y²=0
(2x-y)(x-y)=0
所以x=1/2y,或x=y
若x=1/2y
x/y+y/x=5/2
若x=y
x/y+y/x=2
选A
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