已知a²-a-4=0,求a²-2（a²-a+3）-1/2(a²-a-4)-a的值

已知a²-a-4=0,求a²-2（a²-a+3）-1/2(a²-a-4)-a的值
已知a²-a-4=0,求a²-2（a²-a+3）-1/2(a²-a-4)-a的值

已知a²-a-4=0,求a²-2（a²-a+3）-1/2(a²-a-4)-a的值
a²-a-4=0
a²-a=4
a²-2（a²-a+3）-1/2(a²-a-4)-a
=a²-2a²+2a-6-a
=-a²+a-6
=-(a²-a)-6
=-4-6
=-10