9. What is the sum of the roots of the polynomial shown below?
f(x) = x^3+2x^2-11x-12
My work:
x^3 +2*x^2 -11*x -12 = 0 =>
=> x^3 +2*x^2 -11*x -12 = 0
=> (x -3)*(x +4)*(x +1) = 0
the roots are 3,-4,-1
I just add them,
3+(-4)+(-1)=-2
f(x) = x^3+2x^2-11x-12
My work:
x^3 +2*x^2 -11*x -12 = 0 =>
=> x^3 +2*x^2 -11*x -12 = 0
=> (x -3)*(x +4)*(x +1) = 0
the roots are 3,-4,-1
I just add them,
3+(-4)+(-1)=-2
-
I got the same roots, and the same sum.