a-2+4/(a+2)=(a-2)/1+4/(a+2)
=(a-2)(a+2)/(a+2)+4/(a+2)
=(a²-4)/(a+2)+4/(a+2)
=(a²-4+4)/(a+2)
=a²/(a+2)
此题把a一2看作一个整体,通分较好,把a与2分开通分,2前边是"一"号,还得注意分子加减时变号,易错.
a-2+4/(a+2)=(a-2)/1+4/(a+2)
=(a-2)(a+2)/(a+2)+4/(a+2)
=(a²-4)/(a+2)+4/(a+2)
=(a²-4+4)/(a+2)
=a²/(a+2)
此题把a一2看作一个整体,通分较好,把a与2分开通分,2前边是"一"号,还得注意分子加减时变号,易错.