Assignment:
The equation x4 – 18x3 + 121x2 – 368x + 420=0
has complex conjugate roots (4+j2) & (4-j2). By a process of division and solving a quadratic equation, find all the roots and hence write down all the factors of :
x4 – 18x3 + 121x2 – 368x + 420
Provide complete and step by step solution for the question and show calculations and use formulas.