What are the roots of 3x^4-28x^3-3x^2+112x-36=0?

1 Answer
Aug 3, 2017

3x^4-28x^3-3x^2+112x-36=0

3x^4-12x^2-28x^3+112x+9x^2-36=0

3x^2*(x^2-4)-28x*(x^2-4)+9*(x^2-4)=0

(x^2-4)*(3x^2-28x+9)=0

(x+2)* (x-2)* (3x^2-27x+x+9)=0

(x+2)* (x-2)* (3x-1)* (x-9)=0

From these multipliers, roots of it x=-2, x=2, x=1/3 and x=9.

Explanation:

1) I regrouped terms.

2) I found multipliers

3) I found roots.