• If  and  are the roots of the Quadratic Equation , then  and  

                                          OR
       and

• Sum and products of the roots  and  of  is given by  and
•  is called Discriminant of 
• The roots of the quadratic  are
  1. imaginary if  is negative.
  2. real if  is positive or zero.
  3. real and equal if  
  4. real and rational if  and  is a perfect square or zero.
  5. Real and irrational if  and  is not a perfect square.
• The equation whose roots are  and  (given) is given by
• ,  and  where  and   are called cube root of unity.
•  and  are called the complex cube root of unity.
• Each of the complex cube roots of unity is the square of the other.
• The sum of the cube roots of unity is zero. i.e.,
• 
• If , and  are the roots of  then ,  and
• If ,, and  are the roots of  then , , ,