What is the sum of the roots of the polynomialshown below?
f(x)=3x^3+12x^2+3x-18

Question

anonymous · Answer

factor a 3 and u can "see" 1 root

jim_thompson5910 · Answer

Hint: The sum of the roots of the polynomial $$a_nx^n+a_{n-1}x^{n-1}+\cdots+a_1x+a_0$$ is $$-\frac{a_{n-1}}{a_n}$$ See link below for more info http://www.slideshare.net/kliegey524/polynomials-sum-and-product-of-the-roots

anonymous · Answer

Didn't know that formula, I checked, -6,1,1. Thanks.

jim_thompson5910 · Answer

It turns out that the roots are -3,-2, and 1. Add them up to get -4.


We can see that $$a_{n-1}=a_{2}=12$$ and $$a_n=a_3=3$$, so the sum of the roots is $$-\frac{a_{n-1}}{a_n}=-\frac{12}{3}=-4$$

anonymous · Answer

Have to go to polynomial classes, lol

anonymous · Answer

lol yea