20092008²/(20092009²+20092007²-2)

来源：学生作业学帮网编辑：学帮网时间：2024/06/01 17:16:41

20092008²/(20092009²+20092007²-2)
=20092008²/((20092008+1)²+(20092008-1)²-2)
=20092008²/(20092008²+2*20092008²*1+1²+20092008²-2*20092008²*1+1²-2)
=20092008²/(2*20092008²)
=1/2