问题
填空题
若x2-x-1=0,则-x3+2x+2002的值等于______.
答案
∵x2-x-1=0得x2=x+1
∴x3=x2+x,代入-x3+2x+2002中,得
原式=-x2-x+2x+1+2001,
=-(x2-x-1)+2001,
=0+2001,
=2001.
故答案为:2001.
若x2-x-1=0,则-x3+2x+2002的值等于______.
∵x2-x-1=0得x2=x+1
∴x3=x2+x,代入-x3+2x+2002中,得
原式=-x2-x+2x+1+2001,
=-(x2-x-1)+2001,
=0+2001,
=2001.
故答案为:2001.