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Warm Up Solve each equation. 1. 2x 5 = 17 2. Solve each inequality and graph the solutions. 4. 3. 5 < t + 9 6 14 t > 4 a ≤ –8

Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

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Page 1: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

Warm Up

Solve each equation.

1. 2x – 5 = –17

2.

Solve each inequality and graph the solutions.

4.

3. 5 < t + 9

–6

14

t > –4

a ≤ –8

Page 2: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >
Page 3: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

Solve inequalities that contain more than one

operation

Page 4: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

Inequalities that contain more than one

operation require more than one step to solve.

Use inverse operations to undo the operations

in the inequality one at a time.

Page 5: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

Step 1: Undo addition or subtraction

Step 2: Undo multiplication and division

Is your variable isolated?

Page 6: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

Subtracting a number is the same as adding its

opposite.

7 – 2t = 7 + (–2t)

Remember!

Page 7: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

Solving Multi-Step Inequalities

Solve the inequality and graph the solutions.

45 + 2b > 61

45 + 2b > 61

–45 –45

2b > 16

b > 8

0 2 4 6 8 10 12 14 16 18 20

1. Add/ Subtract

2. Multiply/Divide

The solution set is {b:b > 8}.

Page 8: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

8 – 3y ≥ 29

8 – 3y ≥ 29

–8 –8

–3y ≥ 21

y ≤ –7

1. Add/Subtract

2. Multiply/Divide

–10 –8 –6 –4 –2 0 2 4 6 8 10

–7

Solving Multi-Step Inequalities

Solve the inequality and graph the solutions.

The solution set is {y:y –7}.

Page 9: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

Solve and Graph the inequality

1)9 2b13

2)2x 13 9

3)y

512 8

4) 3m 5 17

Page 10: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

To solve more complicated inequalities, you

may first need to simplify the expressions on

one or both sides.

Page 11: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

Simplifying Before Solving Inequalities

Solve the inequality and graph the solutions.

2 – (–10) > –4t

–10 –8 –6 –4 –2 0 2 4 6 8 10

Page 12: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

Simplifying Before Solving Inequalities

Solve the inequality and graph the solutions.

–4(2 – x) ≤ 8

–10 –8 –6 –4 –2 0 2 4 6 8 10

Page 13: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

Now you try…

x > 3

x ≥ -1

x ≤ 2

x < 35

x ≥ -27

1. 3x – 7 > 2 4. x – 4 < 3

5

2. 4x + 1 -3

5. 15 + x ≥ 6

3

3. 2x – 7 ≤ -3

Page 14: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

Lesson Quiz: Part I

Solve each inequality and graph the solutions.

1. 13 – 2x ≥ 21 x ≤ –4

2. –11 + 2 < 3p p > –3

3. 23 < –2(3 – t) t > 7

4.

Page 15: Lesson 9.8 Solving Two-Step Inequalities · 2013-10-13 · Solving Multi-Step Inequalities Solve the inequality and graph the solutions. 45 + 2b > 61 45 + 2b > 61 –45 –45 2b >

Lesson Quiz: Part II

5. A video store has two movie rental plans. Plan A

includes a $25 membership fee plus $1.25 for each

movie rental. Plan B costs $40 for unlimited movie

rentals. For what number of movie rentals is plan B

less than plan A?

more than 12 movies