Algebra 1 · Unit 1
Solve linear inequalities in one variable and graph the solution on a number line.
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Graph on a number line
x > 5 open circle
x ≥ 5 closed circle
Compound inequalities
AND 1 < x ≤ 4
OR x ≤ −2 or x > 3
Compound inequality special cases
x > 3 AND x > 7
x > 3x > 7
AND overlap → x > 7
x > 3 OR x > 7
x > 3x > 7
OR anything shaded works! → x > 3
x > 1 AND x < −3
x > 1x < −3
AND means overlap. No overlap → no solution
x > 1 OR x < −3
x > 1x < −3
OR anything shaded works → infinitely many solutions
Easy example
x + 4 ≤ 9
x ≤ 5
Medium example
−3x + 5 > 14
−3x > 9
x < −3 (flip the sign)
Medium Graph example
x > 5 or x ≤ 1
Medium Write inequality example
−5 < x ≤ 1
Hard AND example
−2 < 3x + 1 ≤ 10
−1 < x ≤ 3
Hard OR example
x + 2 ≤ −1 or 3x > 12
x ≤ −3 or x > 4
Two steps, then graph.
x + 4 ≤ 9
x ≤ 5
Answer: x ≤ 5
x − 3 > 2
x > 5
Answer: x > 5
2x ≤ 10
x ≤ 5
Answer: x ≤ 5
x + 7 ≥ 1
x ≥ −6
Answer: x ≥ −6
5x < 20
x < 4
Answer: x < 4
x + 11 < 5
x < −6
Answer: x < −6
Distribute. When you multiply or divide by a negative, flip the sign.
−3x + 5 > 14
−3x > 9
x < −3 (flip the sign)
Answer: x < −3
2x − 7 ≥ 9
2x ≥ 16
x ≥ 8
Answer: x ≥ 8
4 − x < 1
−x < −3
x > 3 (flip the sign)
Answer: x > 3
3(x + 2) ≤ 15
3x + 6 ≤ 15
3x ≤ 9
x ≤ 3
Answer: x ≤ 3
−4x + 3 ≤ 19
−4x ≤ 16
x ≥ −4 (flip the sign)
Answer: x ≥ −4
−2x + 6 > 0
−2x > −6
x < 3 (flip the sign)
Answer: x < 3
Graph a compound inequality.
x > 5 or x ≤ 1
Answer: x ≤ 1 or x > 5
x ≤ 6 and x ≥ −1
−1 ≤ x ≤ 6
Answer: −1 ≤ x ≤ 6
x > 2 and x > 4
AND overlap → x > 4
Answer: x > 4
x < 0 or x ≥ 3
Answer: x < 0 or x ≥ 3
x < 8 and x < 3
AND overlap → x < 3
Answer: x < 3
x ≥ 2 or x ≤ −4
Answer: x ≤ −4 or x ≥ 2
Write a compound inequality from a graph.
−5 < x ≤ 1
Answer: −5 < x ≤ 1
0 ≤ x ≤ 4
Answer: 0 ≤ x ≤ 4
x ≤ −3 or x ≥ 5
Answer: x ≤ −3 or x ≥ 5
−3 < x < 2
Answer: −3 < x < 2
x < −2 or x > 4
Answer: x < −2 or x > 4
−6 ≤ x < 1
Answer: −6 ≤ x < 1
Rewrite as two inequalities, then solve each piece.
−2 < 3x + 1 ≤ 10
−2 < 3x + 1
−3 < 3x
−1 < x
3x + 1 ≤ 10
3x ≤ 9
x ≤ 3
−1 < x ≤ 3
Answer: −1 < x ≤ 3
1 ≤ 2x − 3 < 7
1 ≤ 2x − 3
4 ≤ 2x
2 ≤ x
2x − 3 < 7
2x < 10
x < 5
2 ≤ x < 5
Answer: 2 ≤ x < 5
−5 < x + 1 ≤ 3
−5 < x + 1
−6 < x
x + 1 ≤ 3
x ≤ 2
−6 < x ≤ 2
Answer: −6 < x ≤ 2
−1 ≤ 4x + 3 < 11
−1 ≤ 4x + 3
−4 ≤ 4x
−1 ≤ x
4x + 3 < 11
4x < 8
x < 2
−1 ≤ x < 2
Answer: −1 ≤ x < 2
2 < 2x − 4 ≤ 8
2 < 2x − 4
6 < 2x
3 < x
2x − 4 ≤ 8
2x ≤ 12
x ≤ 6
3 < x ≤ 6
Answer: 3 < x ≤ 6
−4 < 2(x − 1) ≤ 6
−4 < 2(x − 1)
−2 < x − 1
−1 < x
2(x − 1) ≤ 6
x − 1 ≤ 3
x ≤ 4
−1 < x ≤ 4
Answer: −1 < x ≤ 4
Solve each piece, then graph both rays.
x + 2 ≤ −1 or 3x > 12
x + 2 ≤ −1
x ≤ −3
3x > 12
x > 4
x ≤ −3 or x > 4
Answer: x ≤ −3 or x > 4
x − 5 ≥ 1 or 2x < −8
x − 5 ≥ 1
x ≥ 6
2x < −8
x < −4
x < −4 or x ≥ 6
Answer: x < −4 or x ≥ 6
4x + 1 ≤ 9 or x − 3 > 2
4x + 1 ≤ 9
4x ≤ 8
x ≤ 2
x − 3 > 2
x > 5
x ≤ 2 or x > 5
Answer: x ≤ 2 or x > 5
−2x ≥ 6 or x + 5 > 8
−2x ≥ 6
x ≤ −3 (flip the sign)
x + 5 > 8
x > 3
x ≤ −3 or x > 3
Answer: x ≤ −3 or x > 3
3(x − 2) < 3 or 4x ≥ 20
3(x − 2) < 3
3x − 6 < 3
3x < 9
x < 3
4x ≥ 20
x ≥ 5
x < 3 or x ≥ 5
Answer: x < 3 or x ≥ 5
5 − x < 1 or 2x + 4 ≤ 0
5 − x < 1
−x < −4
x > 4 (flip the sign)
2x + 4 ≤ 0
2x ≤ −4
x ≤ −2
x ≤ −2 or x > 4
Answer: x ≤ −2 or x > 4
AND and OR that collapse, plus no solution and all real numbers.
x > 2 and x > 6
AND overlap → x > 6
Answer: x > 6
x > 1 and x > 4
AND overlap → x > 4
Answer: x > 4
x > 1 or x > 4
OR anything shaded works! → x > 1
Answer: x > 1
x < 5 and x < 2
AND overlap → x < 2
Answer: x < 2
x < 5 or x < 2
OR anything shaded works! → x < 5
Answer: x < 5
x > 1 and x < −3
AND means overlap. No overlap → no solution
Answer: no solution
x > 1 or x < −3
OR anything shaded works → infinitely many solutions
Answer: infinitely many solutions
2x + 9 > 2x + 4
9 > 4
Answer: all real numbers
6x − 5 < 6x − 12
−5 < −12
Answer: no solution
12x − 4 ≥ 14x + 1
2x − 16 ≥ x + 4
x − 16 ≥ 4
x ≥ 20
Answer: x ≥ 20
2x + 3 > 9 and x + 5 > 10
2x + 3 > 9
2x > 6
x > 3
x + 5 > 10
x > 5
AND overlap → x > 5
Answer: x > 5
3x < 12 or x − 1 < 5
3x < 12
x < 4
x − 1 < 5
x < 6
OR anything shaded works! → x < 6
Answer: x < 6
x + 4 > 6 and 2x < −8
x + 4 > 6
x > 2
2x < −8
x < −4
AND means overlap. No overlap → no solution
Answer: no solution
x + 4 > 6 or 2x < −8
x + 4 > 6
x > 2
2x < −8
x < −4
OR anything shaded works → infinitely many solutions
Answer: infinitely many solutions
4x + 7 > 4x + 1
7 > 1
Answer: all real numbers
5x − 2 < 5x − 9
−2 < −9
Answer: no solution
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