The potential rational roots are ± the factors of the
last term (in absolute value).

±1, ±2, ±3, ±6

We try 1

1 |1  1 -5 -3  6
  |   1  2 -3 -6
   1  2 -3 -6  0

So we have factored the equation as:



We can factor the expression in the second parentheses
by grouping, ie., factor the first two terms and factor
the last two terms:



Factor (x+2) out of the big parentheses:



Use zero-factor property:

; ; 
;    ;  
                   

The irrational roots are  and .

Their sum is 0.

Edwin