整数x.y互为相反数,即x=﹣y（2x+y)(x+2y)与-1/25的倒数相等,即（2x+y)(x+2y)=﹣25所以（2x+y)(x+2y)=（﹣2y＋y）(﹣y＋2y)=﹣y²=﹣25 y²=25 y=±5 x=﹣5和5所以x-y=5－（﹣5）=10或者x-y=﹣5－5=﹣1...