I am currently doing a subject called 'Linear Algebra for data analysis'. I am simply having trouble with a fundamental factorising element when finding my eigenvalues from a matrix. If for example I have found the following.....
-1 as a factor of x^3+x^2+2x-4 , how do I find the remaining eigenvalues?
Complete the cubic knowing $\;x-1\;$ divides it:
$$x^3+x^2+2x-4=(x-1)(x^2+2x+4)$$
Now use the usual formula for the roots of a quadratic. You shall get a conjugate pair of complex non-real roots.