Find all the zeros of f(x).
1 answer:
Answer:
-2, -1, -1, 1/3
Step-by-step explanation:
A graphing calculator can find the real roots of a polynomial pretty easily. The attached graph of this function shows its zeros to be ...
-2, -1, -1, 1/3
__
The rational root theorem tells you that rational roots will be from the set ...
{±1/3, ±2/3, ±1, ±2}
Descarte's rule of signs tells you there will be 1 positive real root. The sum of coefficients is 24 (a relatively large positive number), so it is certain the positive root will be less than 1.
The sum of coefficients of odd-degree terms (11+1) is equal to the sum of coefficients of even-degree terms (3+11-2), telling you that -1 is a root. Synthetic division gives the cubic factor as 3x³ +8x² +3x -2, which has the same characteristics as the original quartic. That is, there is one positive real root, and -1 is a root of the cubic (hence a double root of f(x)).
Another round of synthetic division reveals the quadratic factor to be 3x² +5x -2, which can be factored as (x +2)(3x -1) to reveal the remaining roots.
You might be interested in