What is the sum of the roots of the polynomial shown below?

f(x)=3x^3+12x^2+3x-18

You can use Ruffini to find the roots:

      3      + 12    +3      -18

1            +3      +15    +18
    
    3        +15   +18        0

-2             -6    -18
  
     3         +9        0

-3            -9
   
     3        0

Then the roots are 1, -2 and - 3

Their sum is 1 - 2 - 3 = - 4

The sum of the roots of a cubic equation can be obtained using:
-b/a; where a is the coefficient of x³ and b is the coefficient of x²
sum = -12/3
= -4

The 3rd quadrant as 3x+g5ti=56i: 92d-543