Question

已知x平方加x加1等于零,求x的3次加2x平方加2x加3的值

Answer 1

x^2+x+1=0

x^2+x=-1

x^3+2x^2+2x+3

=x^3+x^2+x^2+2x+3

=x(x^2+x)+x^2+2x+3

=-x+x^2+2x+3

=x^2+x+3

=-1+3

=2