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PLEASE PLEASE PLEASE HELPPP MEEE !!! Identify all of the roots of the function.

f(x) = x3 – 5x2 – 2x + 24

User Nicolabo
by
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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
5.2k points
4 votes

Answer:

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

User Elbrant
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5.7k points