a的二次方-4分之4+a+2分之2-a-2分之1
问题描述：
a的二次方-4分之4+a+2分之2-a-2分之1
答
=4/(a+2)(a-2)+2(a-2)/(a+2)(a-2) -(a+2)/(a+2)(a-2)
=[4+2(a-2)-(a+2)]/(a+2)(a-2)
=(4+2a-4-a-2)/(a+2)(a-2)
=(a-2)/(a+2)(a-2)
=1/(a+2)