How do I make sense of my solution to x^3 -3*x^2 +2*x - 12 == 0?

I got one real and 2 imaginary roots. But by Descartes' Rule of signs, there are three sign changes in this equation and we are suppose to have 3 real roots. However, MATLAB gives one real and two...

21 March 2014 1,873 6 View