Discover the answers you need at Westonci.ca, a dynamic Q&A platform where knowledge is shared freely by a community of experts. Connect with a community of experts ready to help you find solutions to your questions quickly and accurately. Our platform provides a seamless experience for finding reliable answers from a network of experienced professionals.

Graph the following polynomial function by hand. Then solve the equation and inequalities.

[tex]\[
\begin{aligned}
P(x) & =x^4+4x^3-3x^2-18x \\
& =x(x-2)(x+3)^2
\end{aligned}
\][/tex]

(a) [tex]\(P(x)=0\)[/tex]

(b) [tex]\(P(x) \geq 0\)[/tex]

(c) [tex]\(P(x) \leq 0\)[/tex]

(a) The solution set for [tex]\(P(x)=0\)[/tex] is [tex]\(\{ \square \}\)[/tex].

(Use a comma to separate answers as needed.)

Sagot :

Let's solve the given polynomial function step-by-step.

The polynomial function is given by:
[tex]\[ P(x) = x^4 + 4x^3 - 3x^2 - 18x \][/tex]
which is already factored as:
[tex]\[ P(x) = x(x - 2)(x + 3)^2 \][/tex]

### (a) Solve [tex]\( P(x) = 0 \)[/tex]

To find the values of [tex]\( x \)[/tex] for which [tex]\( P(x) = 0 \)[/tex], we set each factor equal to zero:
[tex]\[ x = 0 \][/tex]
[tex]\[ x - 2 = 0 \implies x = 2 \][/tex]
[tex]\[ (x + 3)^2 = 0 \implies x + 3 = 0 \implies x = -3 \][/tex]

Therefore, the solution set for [tex]\( P(x) = 0 \)[/tex] is:
[tex]\[ \{ -3, 0, 2 \} \][/tex]

### (b) Solve [tex]\( P(x) \geq 0 \)[/tex]

To solve [tex]\( P(x) \geq 0 \)[/tex], we need to determine where the polynomial [tex]\( P(x) \)[/tex] is non-negative. We will analyze the sign of [tex]\( P(x) \)[/tex] over the intervals determined by the roots [tex]\(-3\)[/tex], [tex]\(0\)[/tex], and [tex]\(2\)[/tex]. The critical points divide the real line into the following intervals:
[tex]\[ (-\infty, -3), (-3, 0), (0, 2), (2, \infty) \][/tex]

We will test the sign of [tex]\( P(x) \)[/tex] within each interval by selecting a test point from each interval and determining the corresponding sign of [tex]\( P(x) \)[/tex].

1. Interval [tex]\((- \infty, -3)\)[/tex]: Choose [tex]\( x = -4 \)[/tex]
[tex]\[ P(-4) = (-4)(-6)(-1)^2 < 0 \][/tex]

2. Interval [tex]\((-3, 0)\)[/tex]: Choose [tex]\( x = -1 \)[/tex]
[tex]\[ P(-1) = (-1)(-3)(2)^2 > 0 \][/tex]

3. Interval [tex]\((0, 2)\)[/tex]: Choose [tex]\( x = 1 \)[/tex]
[tex]\[ P(1) = (1)(-1)(4) < 0 \][/tex]

4. Interval [tex]\((2, \infty)\)[/tex]: Choose [tex]\( x = 3 \)[/tex]
[tex]\[ P(3) = (3)(1)(6)^2 > 0 \][/tex]

Additionally, we need to consider the values at the critical points:
[tex]\[ P(-3) = 0, \quad P(0) = 0, \quad P(2) = 0 \][/tex]

Based on the signs and the fact that the polynomial is zero at the critical points, we have:
[tex]\[ P(x) \geq 0 \text{ on the intervals } [-3, 0] \cup [2, \infty) \][/tex]

### (c) Solve [tex]\( P(x) \leq 0 \)[/tex]

Since we have already analyzed the intervals, [tex]\( P(x) \)[/tex] is non-positive on the remaining intervals:
[tex]\[ P(x) \leq 0 \text{ on the intervals } (-\infty, -3) \cup (0, 2) \][/tex]

### Summary

(a) The solution set for [tex]\( P(x) = 0 \)[/tex] is [tex]\(\{-3, 0, 2\}\)[/tex].

(b) The solution set for [tex]\( P(x) \geq 0 \)[/tex] is [tex]\([ -3, 0 ] \cup [ 2, \infty )\)[/tex].

(c) The solution set for [tex]\( P(x) \leq 0 \)[/tex] is [tex]\(( - \infty, -3) \cup ( 0, 2 )\)[/tex].
Thank you for choosing our service. We're dedicated to providing the best answers for all your questions. Visit us again. We appreciate your time. Please revisit us for more reliable answers to any questions you may have. We're here to help at Westonci.ca. Keep visiting for the best answers to your questions.