# (Q13.) Sample 3 GCC Math 101/120 Common Final Intermediate Algebra | Summary and Q&A

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December 15, 2013
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(Q13.) Sample 3 GCC Math 101/120 Common Final Intermediate Algebra

## TL;DR

Learn how to solve and graph quadratic inequalities using a safe and reliable method.

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### Q: What is the common mistake students make when solving quadratic inequalities?

The common mistake is to incorrectly write down the solutions as separate inequalities with a greater than or less than symbol. This approach does not consider the contradiction it creates in the inequality and leads to incorrect solutions.

### Q: Why is it necessary to convert the quadratic inequality into an equation?

Converting the inequality into an equation allows us to focus on finding the critical points, which are the values of x that make the equation equal to zero. These critical points are crucial for graphing the solutions accurately.

### Q: How do we graph the solutions on a number line?

After finding the critical points, we label them on the number line as open circles. Then, we pick a test number from each interval and plug it into the factored form of the inequality to determine if it is true or false. If true, we shade the corresponding interval as part of the solution.

### Q: Why is the safe method recommended for solving quadratic inequalities?

The safe method ensures accurate solutions and prevents common mistakes. By treating the inequality as an equation and considering the critical points, we can confidently graph the solutions without creating contradictions.

## Summary & Key Takeaways

• The video provides a step-by-step guide on solving and graphing quadratic inequalities.

• It highlights a commonly made mistake when solving quadratic inequalities and emphasizes the correct approach.

• The safe method involves converting the inequality into an equation and determining the critical points before graphing the solutions on a number line.