SOLUTION: A partial solution set is given for the polynomial equation. Find the complete solution set. (Enter your answers as a comma-separated list.) x^3 + 5x^2 − 20x − 42 = 0;

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: A partial solution set is given for the polynomial equation. Find the complete solution set. (Enter your answers as a comma-separated list.) x^3 + 5x^2 − 20x − 42 = 0;      Log On


   

Question 1098886: A partial solution set is given for the polynomial equation. Find the complete solution set. (Enter your answers as a comma-separated list.)
x^3 + 5x^2 − 20x − 42 = 0; {−7}
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
-7   |    1     5     -20     -42
     |
     |         -7      14      42
     |_________________________________
         1     -2      -6       0

You can use general solution of quadratic equation to find the roots of the quadratic factor:

%28x%2B7%29%28x%5E2-2x-6%29=0

-

%282%2B-+sqrt%284%2B4%2A6%29%29%2F2

%282%2B-+2%2Asqrt%287%29%29%2F2

highlight%281%2B-+sqrt%287%29%29--------the two quadratic roots