五四制六年级数学题,已知a平方+a-1=0,求代数式a立方+2a平方+2+020的值是多少

Question

如题所述

Answer 1

a²+a-1=0
a²+a=1
a³+2a²+2020
=a（a²+a+a）+2020
=a（a+1）+2020
=a²+a+2020
=1+2020
=2021