holt mcdougal algebra 1 2-4 solving two-step and multi-step inequalities solve inequalities that...

Holt McDougal Algebra 1

2-4Solving Two-Step and Multi-Step Inequalities

Solve inequalities that contain more than one operation.

Objective



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.



Example 1A: 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



8 – 3y ≥ 298 – 3y ≥ 29–8 –8

–3y ≥ 21

y ≤ –7

–10 –8 –6 –4 –2 0 2 4 6 8 10

–7

Example 1B: Solving Multi-Step Inequalities




Check It Out! Example 1a


–12 ≥ 3x + 6–12 ≥ 3x + 6– 6 – 6

–18 ≥ 3x

–6 ≥ x

–10 –8 –6 –4 –2 0 2 4 6 8 10



Check It Out! Example 1b


x < –11

–5 –5x + 5 < –6

–20 –12 –8 –4–16 0

–11



Check It Out! Example 1c


1 – 2n ≥ 21–1 –1

–2n ≥ 20

n ≤ –10 –10

–20 –12 –8 –4–16 0



Example 2A: Simplifying Before Solving Inequalities


2 – (–10) > –4t

12 > –4t

–3 < t (or t > –3)

–3

–10 –8 –6 –4 –2 0 2 4 6 8 10



Example 2B: Simplifying Before Solving Inequalities


–4(2 – x) ≤ 8

–4(2 – x) ≤ 8

–4(2) – 4(–x) ≤ 8–8 + 4x ≤ 8+8 +8

4x ≤ 16

x ≤ 4

–10 –8 –6 –4 –2 0 2 4 6 8 10



Example 2C: Simplifying Before Solving Inequalities




Check It Out! Example 2a


– 5 > – 5

2m > 20

m > 10

0 2 4 6 8 10 12 14 16 18 20

2m + 5 > 52

2m + 5 > 25



Check It Out! Example 2b


3 + 2(x + 4) > 3

3 + 2(x + 4) > 33 + 2x + 8 > 3

2x + 11 > 3– 11 – 11

2x > –8

x > –4

–10 –8 –6 –4 –2 0 2 4 6 8 10



Check It Out! Example 2c




Example 3: Application

To rent a certain vehicle, Rent-A-Ride charges $55.00 per day with unlimited miles. The cost of renting a similar vehicle at We Got Wheels is $38.00 per day plus $0.20 per mile. For what number of miles is the cost at Rent-A-Ride less than the cost at We Got Wheels?

Let m represent the number of miles. The cost for Rent-A-Ride should be less than that of We Got Wheels.

Cost at Rent-A-Ride

must be less than

daily cost at We Got Wheels

plus$0.20

per miletimes # of

miles.



Check It Out! Example 3

The average of Jim’s two test scores must be at least 90 to make an A in the class. Jim got a 95 on his first test. What grades can Jim get on his second test to make an A in the class?

Let x represent the test score needed. The average score is the sum of each score divided by 2.

First test score

plussecond test score

divided

by

number of scores

is greater than or equal to

total score



Lesson Quiz: Part ISolve 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.



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

holt mcdougal algebra 1 2-4 solving two-step and multi-step inequalities solve inequalities that...

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