题目内容：

已知a的平方-a-1=0,求a的3次方-2a+2009的值

优质解答

a²-a-1=0
a²-a=1
所以原式=a³-a²+a²-2a+2009
=a(a²-a)+a²-2a+2009
=a+a²-2a+2009
=a²-a+2009
=1+2009
=2010