# Solving Polynomial Inequalities | Summary and Q&A

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February 15, 2018
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The Organic Chemistry Tutor
Solving Polynomial Inequalities

## TL;DR

Learn how to solve polynomial inequalities using number lines, factoring, and interval notation.

## Key Insights

• ๐งก Inequalities have a range of answers, while equations have exact answers.
• ๐ซฅ Quadratic inequalities require factoring and analyzing the sign of the factors on a number line.
• 0๏ธโฃ Polynomial inequalities involve factoring by grouping and using the rational zero theorem to find possible zeros.
• ๐ซฅ Number lines help determine the positive and negative regions for the solution.
• โ The solution can be represented in interval notation or using inequalities.
• ๐ซฅ Factors with odd multiplicity change signs on the number line.
• ๐ฅ Rational zero theorem helps in finding the points of interest for factoring.

### Q: How does solving polynomial inequalities differ from solving equations?

Unlike equations where x has an exact answer, inequalities have a range of possible answers for x.

### Q: What is the first step in solving a quadratic inequality?

The first step is to move all terms to one side and then factor the expression.

### Q: How do you determine the positive and negative regions on a number line?

By evaluating the expression for different values of x in each region, the signs of the factors can be determined, indicating if the result is positive or negative.

### Q: What is the rational zero theorem used for in solving polynomial inequalities?

The rational zero theorem is used to list the possible rational zeros of a polynomial, which helps in factoring and finding the points of interest on the number line.

### Q: What does the closed circle symbolize on the number line?

A closed circle indicates that the point is included in the solution, meaning it can be equal to the inequality.

### Q: How do you express the solution using interval notation?

Interval notation is used to represent the solution as a range of values, with brackets indicating inclusion and parentheses indicating exclusion.

### Q: Can the solution be expressed using inequalities?

Yes, the solution can also be represented using inequalities, with the symbols greater than or less than indicating the range of values.

### Q: What factors determine when the signs change on the number line?

The signs of the factors will change when the multiplicity (exponent) of each factor is odd. If the multiplicity is even, the signs will not change.

## Summary & Key Takeaways

• In solving polynomial inequalities, x can have a range of answers rather than an exact answer as in equations.

• To solve a quadratic inequality, factor the expression and create a number line to determine the positive and negative regions.

• To solve a polynomial inequality, move all terms to one side, factor by grouping, and use the rational zero theorem to find possible solutions.

• By analyzing the signs of the factors and using number lines, the positive and negative regions can be identified to determine the solution.