113k views
1 vote
PLEASE PLEASE PLEASE HELPPP MEEE !!! Identify all of the roots of the function.

f(x) = x3 – 5x2 – 2x + 24

User Nicolabo
by
8.2k points

2 Answers

6 votes

Answer:

-2, 3 & 4

Explanation:

The integer roots of the polynomial function f(x)=x^3-5x^2-2x+24f(x)=x

3

−5x

2

−2x+24 can be only among the divisors of free term.

The divisors of free term are:

\pm 1, \pm 2, \pm 3, \pm 4, \pm 6, \pm 8, \pm 12, \pm 24.±1,±2,±3, ±4,±6,±8,±12,±24.

Check them:

1. f(1)=1^3-5\cdot 1^2-2\cdot 1+24=18\\eq 0f(1)=1

3

−5⋅1

2

−2⋅1+24=18

=0 , 1 is not a root.

2. f(-1)=(-1)^3-5\cdot (-1)^2-2\cdot (-1)+24=20\\eq 0f(−1)=(−1)

3

−5⋅(−1)

2

−2⋅(−1)+24=20

=0 , -1 is not a root.

3. f(2)=2^3-5\cdot 2^2-2\cdot 2+24=8\\eq 0f(2)=2

3

−5⋅2

2

−2⋅2+24=8

=0 , 2 is not a root.

4. f(-2)=(-2)^3-5\cdot (-2)^2-2\cdot (-2)+24=0f(−2)=(−2)

3

−5⋅(−2)

2

−2⋅(−2)+24=0 , -2 is a root.

5. f(3)=3^3-5\cdot 3^2-2\cdot 3+24=0f(3)=3

3

−5⋅3

2

−2⋅3+24=0 , 3 is a root.

6. f(-3)=(-3)^3-5\cdot (-3)^2-2\cdot (-3)+24=-42\\eq 0f(−3)=(−3)

3

−5⋅(−3)

2

−2⋅(−3)+24=−42

=0 , -3 is not a root.

7. f(4)=4^3-5\cdot 4^2-2\cdot 4+24=0f(4)=4

3

−5⋅4

2

−2⋅4+24=0 , 4 is a root.

The cubic function has at most 3 roots, then

Answer: roots of the function are -2, 3 and 4.

User Butters
by
7.9k points
4 votes

Answer:

4, 3, -2 are the 3 roots of the function

User Elbrant
by
9.1k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories