已知X=2.5,Y=1,求分式-X²+8XY-15Y²/X²-3XY-10Y²的值谢谢

已知X=2.5,Y=1,求分式-X²+8XY-15Y²/X²-3XY-10Y²的值谢谢
已知X=2.5,Y=1,求分式-X²+8XY-15Y²/X²-3XY-10Y²的值
谢谢

已知X=2.5,Y=1,求分式-X²+8XY-15Y²/X²-3XY-10Y²的值谢谢
原式＝－（x－3y）(x－5y)/(x－5y)(x＋2y)＝－（x－3y）/(x＋2y)＝－1/9

-(X-3Y)(X-5Y)/(X-5Y)(X+2Y)
=-X+3Y/X+2Y(X不等於5Y)
=0.5/4.5
=1/9