Chapter 3: Problem 72
Solve each inequality by using the test-point method. State the solution set in interval notation and graph it. $$-5-s^{2}<0$$
Short Answer
Expert verified
The solution set is \( (-\infty, \infty) \).
Step by step solution
01
Simplify the Inequality
First, isolate the quadratic term. Start with the given inequality \( -5 - s^2 < 0 \). Add 5 to both sides to get \( -s^2 < 5 \). Next, multiply both sides by -1 (remember to reverse the inequality sign when multiplying or dividing by a negative number): \( s^2 > -5 \).
02
Analyze the Inequality
Since \( s^2 \) represents a squared term and is always non-negative, the inequality \( s^2 > -5 \) is always true for all real numbers \( s \). Thus, every value of \( s \) satisfies this inequality.
03
State the Solution Set
Since the inequality is true for all real numbers, the solution set in interval notation is \( (-\infty, \infty) \).
04
Graph the Solution Set
On a number line, shade the entire line to represent all real numbers.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
quadratic inequality
A quadratic inequality is an inequality that involves a quadratic expression. Quadratic expressions have the general form \( ax^2 + bx + c \), where \( a, b, \) and \( c \) are constants, and \( x \) represents the variable. These inequalities are used to express ranges of values that satisfy the quadratic condition, rather than a specific solution like a quadratic equation. Examples include \( x^2 - 4x + 3 > 0 \) or \( -5 - s^2 < 0 \). Quadratic inequalities can be solved using various methods, including factoring, completing the square, or using the Quadratic Formula. For our exercise, the inequality \( -5 - s^2 < 0 \) was given, and we simplified it to find a solution.
test-point method
The test-point method is a technique to determine the solution set of an inequality. To apply this method:
- First, simplify the inequality to a standard form.
- Find the critical points, usually by setting the expression equal to zero.
- Divide the number line into intervals based on these critical points.
- Select a test point from each interval and substitute it into the original inequality to check if it satisfies the inequality.
interval notation
Interval notation is a way to represent the solution set of inequalities. Intervals show the range of values that satisfy the condition. Types of intervals include:
- Open intervals: Use parentheses ( ), indicating the endpoints are not included. Example: \( (a, b) \).
- Closed intervals: Use brackets [ ], indicating the endpoints are included. Example: \( [a, b] \).
- Half-open/half-closed intervals: Combine a parenthesis and a bracket. Example: \( [a, b) \).
graphing inequalities
Graphing inequalities involves representing the solution set on a number line for one-variable inequalities or on a coordinate plane for two-variable inequalities. For our one-variable inequality:
- Identify the solution set: Use techniques like the test-point method.
- Shade the solution area: On a number line, shade the portion that includes all solutions. Use open or closed dots to indicate whether endpoints are included.
- Label correctly: Ensure clarity by labeling intervals and points correctly.