College

Find all of the zeros and multiplicities of the function [tex]f(x)=x^5+x^4-19x^3+17x^2+48x-60[/tex].

1. Begin by finding the possible rational zeros by applying the Rational Zero Theorem.

2. Graph the function on your calculator and make predictions of rational zeros from the graph.

3. Check your predictions using synthetic division.

4. Solve the remaining quadratic to find all the zeros.

Show all work.

Answer :

To solve the problem of finding all zeros and their multiplicities for the polynomial function [tex]\( f(x) = x^5 + x^4 - 19x^3 + 17x^2 + 48x - 60 \)[/tex], we can use a systematic approach. Let's go through the solution step by step.

### Step 1: Apply the Rational Zero Theorem

The Rational Zero Theorem suggests that possible rational zeros of a polynomial function are the factors of the constant term divided by the factors of the leading coefficient.

- Constant term: [tex]\(-60\)[/tex]
- Leading coefficient: [tex]\(1\)[/tex]

Thus, the possible rational zeros are the factors of [tex]\(-60\)[/tex], which include:

[tex]\[ \pm 1, \pm 2, \pm 3, \pm 4, \pm 5, \pm 6, \pm 10, \pm 12, \pm 15, \pm 20, \pm 30, \pm 60 \][/tex]

### Step 2: Graph the Function

By graphing the function using a graphing calculator, we can visually inspect potential zeros.

### Step 3: Determine Zeros

Using the graph, we can identify some likely candidates for the zeros. In this case, from the analysis, we find:

1. The zero [tex]\( x = -5 \)[/tex]
2. The zero [tex]\( x = 2 \)[/tex]

### Step 4: Verify Zeros Using Synthetic Division

To confirm these values, we would perform synthetic division with each candidate zero identified:

- Check [tex]\( x = -5 \)[/tex]: When you divide the polynomial by [tex]\( x + 5 \)[/tex], the remainder is 0, thus confirming it as a zero.
- Check [tex]\( x = 2 \)[/tex]: When you divide the polynomial by [tex]\( x - 2 \)[/tex], the remainder is also 0, confirming this as a zero as well.

### Step 5: Solve Remaining Polynomials

After confirming the zeros, we find additional zeros from the polynomial through calculation or additional methods.

From a deeper calculation:

- Other found zeros are approximately [tex]\(-1.732\)[/tex] and [tex]\(1.732\)[/tex].

### Step 6: State All Zeros

Thus, the zeros of the polynomial [tex]\( f(x) \)[/tex] include:

- [tex]\( x = -5 \)[/tex] with a multiplicity of 1
- [tex]\( x = 2 \)[/tex] with a multiplicity of 1
- [tex]\( x \approx -1.732\)[/tex], a complex conjugate pair
- [tex]\( x \approx 1.732\)[/tex], a complex conjugate pair

### Conclusion

The function [tex]\( f(x) = x^5 + x^4 - 19x^3 + 17x^2 + 48x - 60 \)[/tex] has the zeros:

- [tex]\( -5 \)[/tex]
- [tex]\( 2 \)[/tex]
- Approximately [tex]\(-1.732\)[/tex]
- Approximately [tex]\(1.732\)[/tex]

Each zero reflects where the function crosses or touches the x-axis, describing the behavior of the function completely in terms of its roots.