How do you solve a linear inequality in one variable, and why does the inequality sign flip when you multiply or divide by a negative?
Solve linear inequalities in one variable, graph the solution on a number line, and interpret the solution set in context (A.PAR, Patterning and Algebraic Reasoning).
A Georgia Milestones Algebra: Concepts & Connections answer on solving linear inequalities in one variable, the rule that the inequality reverses when multiplying or dividing by a negative, graphing solutions with open and closed circles, and interpreting solution sets in real contexts.
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What this topic is asking
This Patterning and Algebraic Reasoning (A.PAR) standard extends equation solving to inequalities in one variable. The method is almost identical to solving an equation, with one crucial difference: the inequality sign reverses whenever you multiply or divide both sides by a negative number. On the Georgia Milestones EOC, inequalities appear as numeric or hot-spot items where you solve and then represent the solution on a number line, and as multiple-choice items that translate a phrase like "at most" or "at least" into the correct inequality. Reading those phrases correctly and remembering the sign flip are the two skills being tested.
Solving like an equation, with one exception
To solve an inequality, isolate the variable using the same steps as for an equation: distribute, clear fractions, collect like terms, and divide. The one rule that differs:
To see why the flip is needed, note that is true, but multiplying both sides by gives and , and , so the direction must reverse to keep the statement true.
Graphing the solution on a number line
The solution set is a ray (or segment) on the number line.
- Open circle at the endpoint for strict inequalities or (the endpoint is not a solution).
- Closed circle at the endpoint for or (the endpoint is a solution).
- Shade toward the values that satisfy the inequality: right for "greater than," left for "less than."
For : closed circle at , shade right. For : open circle at 4, shade left.
Translating words into inequalities
EOC word problems use phrases that map to specific symbols.
- "at most," "no more than," "maximum" map to .
- "at least," "no less than," "minimum" map to .
- "more than," "greater than" map to .
- "fewer than," "less than" map to .
A budget of "at most 4 base and 4 + 2m \le 30m \le 13$ miles.
How the Milestones examines this topic
- Numeric or hot-spot. Solve an inequality and select the correct number-line graph (open versus closed circle, correct direction).
- Multiple choice. Match a context phrase to the correct inequality, with sign-direction distractors.
- Constructed response. Solve a multi-step inequality and interpret the solution set in context, stating units.
Why the endpoint type matters in context
The open-versus-closed-circle distinction is not just notation; it changes the answer to a real question. If a ride costs "at most 4 + 2m \le 30m \le 134 + 2(13) = 3030," then 13 miles would cost exactly 30 and would not qualify, so the endpoint is excluded with an open circle and the largest whole-mile answer becomes 12. Reading whether the boundary value itself is allowed is exactly the interpretive step the EOC rewards, and it is the difference between and .
Try this
Q1. Solve and describe the graph. [1 point]
- Cue. , so ; open circle at 4, shade right.
Q2. Solve . [1 point]
- Cue. Multiply by and flip: .
Exam-style practice questions
Practice questions written in the style of GaDOE exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Milestones (style)2 marksHot spot. Solve and describe the graph of the solution on a number line.Show worked answer →
The solution is .
Subtract 5 from both sides: . Divide by and reverse the inequality (dividing by a negative): . On a number line, place a closed circle at (because includes ) and shade to the right (all values greater than ). The reversal of the sign when dividing by a negative is the single most tested idea here.
Milestones (style)1 marksMultiple choice. A taxi charges a 2 per mile. For a budget of at most m4 + 2m \ge 304 + 2m \le 302 + 4m \le 304 + 2m = 30$Show worked answer →
The correct answer is (B).
"At most 4 + 2m \le 30m2m \le 26m \le 13\le\ge$.
Related dot points
- Solve linear equations in one variable, including equations with variables on both sides and rational coefficients, and identify equations with one, none, or infinitely many solutions (A.PAR, Patterning and Algebraic Reasoning).
A Georgia Milestones Algebra: Concepts & Connections answer on solving linear equations in one variable, clearing fractions, collecting variables on one side, and recognizing when an equation has one solution, no solution (a false statement), or infinitely many solutions (an identity).
- Graph linear inequalities in two variables using a boundary line and shading, and find the solution region of a system of linear inequalities (A.PAR, Patterning and Algebraic Reasoning).
A Georgia Milestones Algebra: Concepts & Connections answer on graphing linear inequalities in two variables, choosing a solid or dashed boundary line, shading the correct half-plane with a test point, and finding the overlapping solution region of a system of linear inequalities.
- Write linear equations in two variables from a slope and a point, from two points, and from a real-world context, and interpret slope and intercept in the model (A.PAR, Patterning and Algebraic Reasoning).
A Georgia Milestones Algebra: Concepts & Connections answer on writing the equation of a line from a slope and a point, from two points using the slope formula then point-slope form, and from a real-world context, with interpretation of the slope as a rate and the y-intercept as a starting value.
- Graph linear equations in two variables and identify key features (slope, x-intercept, y-intercept) from slope-intercept, point-slope, and standard form (A.PAR, Patterning and Algebraic Reasoning).
A Georgia Milestones Algebra: Concepts & Connections answer on graphing linear equations in two variables, using slope-intercept form to plot a line, finding x- and y-intercepts from standard form, and reading slope and intercepts from a graph.
Sources & how we know this
- Georgia's K-12 Mathematics Standards (Algebra: Concepts & Connections) — Georgia Department of Education (2023)
- Georgia Milestones Assessment System — Georgia Department of Education (2024)