x−yx+y=2の場合、x−yx+y-2x+2yx−yの値は______.

x−yx+y=2の場合、x−yx+y-2x+2yx−yの値は______.

x−yx+y=2、x−y=2、x−y=2(x+y)x−yx+y-2x+2yx−y=2(x+y)x+y-2(x+y)2(x+y)=2-1=1のため、1.