Question

若a的平方-a-3=0,求a的三次方-4a的二次方+2的值

Answer 1

a^2-a-3=0,a^2-a=3

a^3-4a^2+2

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

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

=3a-3a^2+2

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

=-9+2=-7