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Solve each equation and inequality. (a) \(3(x+1)^{2}(2 x-1)^{4}+8(x+1)^{3}(2 x-1)^{3}=0\) (b) \(3(x+1)^{2}(2 x-1)^{4}+8(x+1)^{3}(2 x-1)^{3} \geq 0\)

Short Answer

Expert verified
(a) Solutions: \(x = -1, \frac{1}{2}, -\frac{5}{14}\). (b) Solution: \((-\infty, -\frac{5}{14}] \cup [\frac{1}{2}, \infty)\).

Step by step solution

01

Factor Out Common Terms (Equation)

Identify the common factors in the equation. Both terms in the equation contain \((x+1)^{2}\) and \((2x-1)^{3}\). Factor these out:\[3(x+1)^{2}(2x-1)^{4} + 8(x+1)^{3}(2x-1)^{3} = (x+1)^{2}(2x-1)^{3} \left[ 3(2x-1) + 8(x+1) \right] = 0\]
02

Simplify Remaining Factor (Equation)

Simplify the expression inside the brackets:\[3(2x-1) + 8(x+1) = 6x - 3 + 8x + 8 = 14x + 5\]Thus, the equation becomes:\[(x+1)^{2}(2x-1)^{3}(14x+5) = 0\].
03

Solve for Roots (Equation)

Set each factor equal to zero to find the roots:1. \((x+1)^{2} = 0 \Rightarrow x = -1\)2. \((2x-1)^{3} = 0 \Rightarrow 2x - 1 = 0 \Rightarrow x = \frac{1}{2}\)3. \(14x + 5 = 0 \Rightarrow 14x = -5 \Rightarrow x = -\frac{5}{14}\)The solutions are \(x = -1\), \(x = \frac{1}{2}\), and \(x = -\frac{5}{14}\).
04

Factor Out Common Terms (Inequality)

The inequality has the same common factors as the equation. Factor them out:\[3(x+1)^{2}(2x-1)^{4} + 8(x+1)^{3}(2x-1)^{3} \geq 0\]Factor out common terms:\[(x+1)^{2}(2x-1)^{3} \left[ 3(2x-1) + 8(x+1) \right] \geq 0\].
05

Simplify and Analyze the Inequality

Simplify inside the brackets, as done earlier:\[(x+1)^{2}(2x-1)^{3}(14x+5) \geq 0\]The inequality is satisfied when all individual factors together produce a non-negative product.
06

Sign Analysis on Each Interval

Perform a sign analysis using the critical points found in the equation part: \(x = -1\), \(x = \frac{1}{2}\), and \(x = -\frac{5}{14}\). Assess the sign of each factor in intervals divided by these critical points:- **Interval 1:** \((x < -1)\)- **Interval 2:** \((-1 < x < -\frac{5}{14})\)- **Interval 3:** \((-\frac{5}{14} < x < \frac{1}{2})\)- **Interval 4:** \((x > \frac{1}{2})\)For each interval, assess the sign of each product.
07

Determine Solution Set for Inequality

Combine intervals where the product is non-negative.- For \(x < -1\), the product is positive.- For \(x = -1\), the product is zero.- For \(-1 < x < -\frac{5}{14}\), the product is positive.- For \(x = -\frac{5}{14}\), the product is zero.- For \(-\frac{5}{14} < x < \frac{1}{2}\), the product is negative.- For \(x = \frac{1}{2}\), the product is zero.- For \(x > \frac{1}{2}\), the product is positive.Thus, the solution set is: \((-\infty, -\frac{5}{14}] \cup [\frac{1}{2}, \infty)\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Factoring
Factoring is a crucial mathematical process that involves breaking down expressions into simpler terms, or "factors," which, when multiplied together, produce the original expression. This technique is especially useful for solving polynomial equations. In the given exercise, both terms contain common factors
  • \((x+1)^{2}\) and
  • \((2x-1)^{3}\).
The process begins by identifying these common factors. This allows us to simplify the equation greatly, presenting it in a more workable form.
The expression after factoring out the common terms becomes:\[(x+1)^{2}(2x-1)^{3} \left[ 3(2x-1) + 8(x+1) \right] = 0\]Factoring is particularly important because it reduces complex expressions and makes them easier to analyze and solve. Once the expression is factored, each factor can be handled separately, as individual equations or inequalities.
In summary, factoring serves as a powerful stepping stone for finding solutions in both polynomial equations and inequalities.
Inequalities
Inequalities involve expressions that use signs like \(<\), \(>\), \(\leq\), or \(\geq\), depicting that one side is not equal but either smaller or larger than the other. In the problem presented, we deal with a polynomial inequality:
  • \[(x+1)^{2}(2x-1)^{3}(14x+5) \geq 0\].
Solving this inequality means determining the sets of values for \(x\) that make this statement true.
A strategic method is performing "sign analysis." This involves testing the sign (positive or negative) of the entire product over intervals defined by critical points (roots from the equation part). We then identify where the entire expression remains non-negative.
For the intervals:
  • \((x < -1)\)
  • \((-1 < x < -\frac{5}{14})\)
  • \((-\frac{5}{14} < x < \frac{1}{2})\)
  • \((x > \frac{1}{2})\)

analysis of each segment reveals where the inequality holds.
As a result, the solution set is \[(-\infty, -\frac{5}{14}] \cup [\frac{1}{2}, \infty)\],indicating all the intervals \(x\) can take for the compound product to be zero or positive.
Roots of Equations
Finding the roots of an equation is an essential task in solving polynomial equations. Roots are specific values of \(x\) that satisfy the equation, making it equal to zero. For the equation \[(x+1)^{2}(2x-1)^{3}(14x+5) = 0\],we identify roots by setting each factor to zero one at a time.
  • The factor \((x+1)^{2} = 0\) gives us the root \(x = -1\).
  • The factor \((2x-1)^{3} = 0\) leads to \(x = \frac{1}{2}\).
  • Similarly, the factor \(14x + 5 = 0\) results in \(x = -\frac{5}{14}\).
Each root tells us an essential detail about where the polynomial crosses the x-axis. These places are also crucial when analyzing inequalities, as transitions between positive and negative regions occur at these points.
Understanding where the equation is zero helps in comprehending the behavior of the polynomial overall. It is pivotal for analyzing the feasibility and range of solutions for related inequalities.

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Most popular questions from this chapter

For each polynomial function, (a) list all possible rational zeros, (b) use a graph to eliminate some of the possible zeros listed in part (a), (c) find all rational zeros, and (d) factor \(P(x)\). $$P(x)=x^{3}-2 x^{2}-13 x-10$$

For each polynomial function, do the following in order. (a) Use Descartes' rule of signs to find the possible number of positive and negative real zeros. (b) Use the rational zeros theorem to determine the possible rational zeros of the function. (c) Find the rational zeros, if any. (d) Find all other real zeros, if any. (e) Find any other nonreal complex zeros, if any. (f) Find the \(x\) -intercepts of the graph, if any. (g) Find the \(y\) -intercept of the graph. (h) Use synthetic division to find \(P(4),\) and give the coordinates of the corresponding point on the graph. (i) Determine the end behavior of the graph. (i) Sketch the graph. (You may wish to support your answer with a calculator graph.) $$P(x)=-2 x^{4}-x^{3}+x+2$$

For each polynomial function, do the following in order. (a) Use Descartes' rule of signs to find the possible number of positive and negative real zeros. (b) Use the rational zeros theorem to determine the possible rational zeros of the function. (c) Find the rational zeros, if any. (d) Find all other real zeros, if any. (e) Find any other nonreal complex zeros, if any. (f) Find the \(x\) -intercepts of the graph, if any. (g) Find the \(y\) -intercept of the graph. (h) Use synthetic division to find \(P(4),\) and give the coordinates of the corresponding point on the graph. (i) Determine the end behavior of the graph. (i) Sketch the graph. (You may wish to support your answer with a calculator graph.) $$P(x)=-x^{5}-x^{4}+10 x^{3}+10 x^{2}-9 x-9$$

Use the rational zeros theorem to factor \(P(x)\). $$P(x)=12 x^{3}+20 x^{2}-x-6$$

Use the given zero to completely factor \(P(x)\) into linear factors. $$\text { Zero: } 2-i ; \quad P(x)=x^{4}-4 x^{3}+9 x^{2}-16 x+20$$

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