For what values of a there are exactly two real numbers that satify the equation:
x^3 + (a-1)x^2 + (9-a)x - 9 = 0
Find all possible answers.
Firstly this is what I have done.
I expand and group which leaves me with:
(x^3 - x^2) + a(x^2 - x) + 9(x - 1) = 0
Then I divide by (x-1) to get x^2 + ax + 9 = 0
Then from there I am lost, would love to know how to finish it off. Thanks! :)