Find the root(s) of [tex]$f(x)=(x+5)^3(x-9)^2(x+1)$[/tex].

A. -5 with multiplicity 3
B. 5 with multiplicity 3
C. -9 with multiplicity 2
D. 9 with multiplicity 2
E. -1 with multiplicity 0
F. -1 with multiplicity 1
G. 1 with multiplicity 0
H. 1 with multiplicity 1



Answer :

To find the roots of the polynomial function [tex]\(f(x) = (x + 5)^3 (x - 9)^2 (x + 1)\)[/tex], we must identify the values of [tex]\(x\)[/tex] that make [tex]\(f(x) = 0\)[/tex]. The roots of the function can be found by setting each factor of the polynomial to zero and solving for [tex]\(x\)[/tex].

Let's break down the polynomial into its factors and find the roots and their corresponding multiplicities:

1. Factor [tex]\( (x + 5) \)[/tex]
- To find the root from this factor, set [tex]\( x + 5 = 0 \)[/tex].
- Solving for [tex]\( x \)[/tex], we get [tex]\( x = -5 \)[/tex].
- The factor [tex]\( (x + 5) \)[/tex] is raised to the power of 3.
- Therefore, [tex]\( x = -5 \)[/tex] is a root with multiplicity 3.

2. Factor [tex]\( (x - 9) \)[/tex]
- To find the root from this factor, set [tex]\( x - 9 = 0 \)[/tex].
- Solving for [tex]\( x \)[/tex], we get [tex]\( x = 9 \)[/tex].
- The factor [tex]\( (x - 9) \)[/tex] is raised to the power of 2.
- Therefore, [tex]\( x = 9 \)[/tex] is a root with multiplicity 2.

3. Factor [tex]\( (x + 1) \)[/tex]
- To find the root from this factor, set [tex]\( x + 1 = 0 \)[/tex].
- Solving for [tex]\( x \)[/tex], we get [tex]\( x = -1 \)[/tex].
- The factor [tex]\( (x + 1) \)[/tex] is raised to the power of 1.
- Therefore, [tex]\( x = -1 \)[/tex] is a root with multiplicity 1.

Now, let's summarize the roots and their multiplicities:

- [tex]\( x = -5 \)[/tex] with multiplicity 3.
- [tex]\( x = 9 \)[/tex] with multiplicity 2.
- [tex]\( x = -1 \)[/tex] with multiplicity 1.

Given the choices, the correct responses are:
- [tex]\( -5 \)[/tex] with multiplicity 3
- [tex]\( 9 \)[/tex] with multiplicity 2
- [tex]\( -1 \)[/tex] with multiplicity 1