Question

已知x²+5xy-6y²=0(y≠0)则代数式x-y/x+y的值为

Answer 1

x²＋5xy－6y²＝（x＋6y）（x－y）＝0
得x＋6y＝0 x－y＝0 x＝－6y x＝y
带入x－y／x＋y得
x－y／x＋y＝7x／－5x＝－7／5
x－y／x＋y＝0／2x＝0

Answer 2

x^2+5xy-6y^2=(x/y)^2+5x/y-6=0
解得x/y=-6或x/y=1
(x-y)/(x+y)=(x/y-1)/(x/y+1)=7/5或0