Pre-calculus; linear inequalities

In summary, the conversation is about solving two quadratic inequalities: 9x^2 + 12x + 4 ≥ 0 and 2 - 5x - 3x^2 ≤ 0. The attempt at solving these inequalities involves factoring and possibly changing the inequalities into a different form. The conversation also addresses a potential error in the second inequality and clarifies that they are quadratic, not linear, inequalities.
  • #1
priscilla98
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Homework Statement



1. 9x^2 + 12x + 4 ≥ 0

2. 2 - 5x - 3x^2 ≤ 0

Homework Equations



The Attempt at a Solution



1. Can't you factor this into (3x + 2) (3x + 2)?
2. Looking at this inequality, I am thinking if you can change this inequality into 3x^2 + 5x + 2.
 
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  • #2
priscilla98 said:

Homework Statement



1. 9x^2 + 12x + 4 ≥ 0

2. 2 - 5x - 3x^2 ≤ 0

Homework Equations



The Attempt at a Solution



1. Can't you factor this into (3x + 2) (3x + 2)?

Yes, you can. So what is your conclusion about the x that satisfy it?

2. Looking at this inequality, I am thinking if you can change this inequality into 3x^2 + 5x + 2.

What you have changed it into isn't an inequality and you likely have a sign error. Did you mean to write 3x2 + 5x - 2 ≥ 0? If so, what next?

Also, your title says linear inequalities. These aren't linear inequalities; they are quadratic inequalities.
 

1. What is a linear inequality in pre-calculus?

A linear inequality in pre-calculus is an algebraic expression that contains a variable, an inequality symbol (such as <, >, ≤, or ≥), and a constant. It represents a range of values that satisfy the inequality, rather than a single value. For example, 2x + 3 < 10 is a linear inequality.

2. How do you graph a linear inequality?

To graph a linear inequality, first isolate the variable on one side of the inequality symbol. Then, treat the inequality symbol as an equal sign and graph the resulting linear equation. Finally, shade the region above or below the line depending on the inequality symbol. If the symbol is < or >, use a dashed line to represent the boundary of the shaded region. If the symbol is ≤ or ≥, use a solid line.

3. What is the solution to a linear inequality?

The solution to a linear inequality is the set of all values that make the inequality true. In other words, it is the range of values that satisfy the inequality. This can be represented on a number line or graphically as a shaded region.

4. How do you solve a system of linear inequalities?

To solve a system of linear inequalities, first graph each inequality individually to determine the shaded regions. Then, find the overlapping region of all the shaded regions. This overlapping region represents the solution to the system of inequalities.

5. How are linear inequalities used in real-life situations?

Linear inequalities are used in many real-life situations, such as setting budgets, determining sales goals, and creating production schedules. They can also be used to represent constraints in optimization problems, such as maximizing profit or minimizing cost. In general, linear inequalities are used to represent relationships between variables and determine the range of values that satisfy those relationships.

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