Mathematics
Grade 9
15 min
Graph inequalities
Graph inequalities
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Identify the four inequality symbols and their meanings.
Translate verbal phrases into algebraic inequalities.
Represent the solution set of a single-variable inequality on a number line.
Correctly use open and closed circles to indicate whether a boundary point is included in a solution set.
Solve and graph multi-step single-variable inequalities.
Graph compound inequalities involving 'and' (intersections) and 'or' (unions).
Write an algebraic inequality from its graph on a number line.
Ever seen a sign that says 'Maximum capacity: 250 people'? How would you show ALL the possible numbers of people allowed? 🧑🤝🧑
This tutorial will teach you how to visually represent all the possible solutions to an inequality on a numb...
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Key Concepts & Vocabulary
TermDefinitionExample
InequalityA mathematical statement that compares two values or expressions that are not equal. It uses one of the following symbols: < (less than), > (greater than), ≤ (less than or equal to), or ≥ (greater than or equal to).x + 5 > 12
Solution SetThe set of all numbers that make an inequality true. For single-variable inequalities, this is often an infinite range of numbers.For x > 7, the solution set includes 7.1, 8, 10, 95, and all other numbers greater than 7.
Boundary PointThe number that separates the solutions from the non-solutions on a number line. It is the value where the expression is equal to the other side.In the inequality x ≤ -2, the boundary point is -2.
Open Circle (Hollow Dot)A symbol used on a number line to indicate that the boundary...
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Core Formulas
Graphing Strict Inequalities
For x > a or x < a, use an open circle at point 'a'.
When the inequality symbol is > (greater than) or < (less than), the boundary point 'a' is not a solution. The open circle visually represents this exclusion. Shade to the right for '>' and to the left for '<'.
Graphing Inclusive Inequalities
For x ≥ a or x ≤ a, use a closed circle at point 'a'.
When the inequality symbol is ≥ (greater than or equal to) or ≤ (less than or equal to), the boundary point 'a' is a solution. The closed circle visually represents this inclusion. Shade to the right for '≥' and to the left for '≤'.
The Sign-Flipping Rule
If you multiply or divide both sides of an ine...
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Challenging
What is the solution to the inequality 7x - 8 < 3x + 12?
A.x < 1
B.x > 5
C.x > 1
D.x < 5
Challenging
A number line graph shows two rays. One ray starts at an open circle at 0 and goes to the left. The other ray starts at a closed circle at 6 and goes to the right. Which compound inequality represents this graph?
A.x < 0 and x ≥ 6
B.x < 0 or x ≥ 6
C.0 < x ≤ 6
D.x ≤ 0 or x > 6
Challenging
The length of a rectangle is 4 inches more than its width, w. If the perimeter of the rectangle must be at most 100 inches, which inequality represents the possible values for the width?
A.w ≤ 23
B.w ≤ 48
C.w ≥ 23
D.w ≥ 48
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