Question

已知a的平方+a+1=0,求a的立方+2a的平方+2a+1

Answer 1

a^3+2a^2+2a+1

=(a^3+a^2+a)+(a^2+a+1)

=a(a^2+a+1)+(a^2+a+1)

=a*0+0

=0