Question 1043460
Expect the remainder for checking the given root to be 0.

<pre>
-2   |   1   2   -7   -20   -12
     |
     |      -2    0    14    12
     |________________________________
        1   0    -7    -6    0
</pre>
This factorization shows f(x)=(x+2)(x^3+0x^2-7x-6) and other factors to check would be -1,-2,-3,1,2,3.


Carry on with synthetic divisions, and you will find the roots to be, for that cubic factor,  -2,-1,3.
{{{f(x)=(x+2)^2(x+1)(x-3)}}}