Chapter 7 Lesson 3Inequalitiespgs. 340-344

What you’ll learn:Write inequalitiesGraph inequalities

VocabularyInequality (340): a mathematical

sentence that contains < or >

Is less thanIs fewer than

Is greater thanIs more thanExceeds

is less than or equal tois no more thanis at most

is greater than or equal to is no less thanis at least

Concept Summary Inequalities

Memorize these signs!!!

Example 1: Write Inequalities with or Your age is less than 15 years

Variable: Let a represent ageInequality: a 15

Your height is greater than 55 inchesVariable: Let h represent heightInequality: h 55

Example 2: Write Inequalities

with or Write an inequality for each sentence.

A number increased by 14 is at least 25

Kyle’s earnings at $15 per hour were no more than $60.

Let n represent the numberRefer to the concept summary to determine whichInequality symbol to use n + 14 25

15h 60

Example 3: Use an InequalityThe elevators in an office building have

been approved for a maximum load of 3600 pounds. Write an inequality to describe a safe load.

Words: the elevators can only hold a max of 3600 pounds This also means that the elevator can hold less than 3600 pounds

Which inequality symbol should we use? Readcarefully to determine! A max of 3600 poundsmeans 3600 pounds or less.

We should use Let m = max weightInequality: m 3600

Example 4: Determine Truth of an Inequality This is like a check for an equation!For the given value, state whether each

inequality is true or falsen + 4 6, n = 12

14 7, c = 2 c

Write the inequality: n + 4 6Replace n with 12: 12 + 4 6

Simplify: 16 6 TRUE! 16 IS greater than or equal to 6

Replace c with 2: 14 7 2

Simplify: 77 FALSE! How could this problem be rewritten to make it true?

By using or

Example 5: Graph Inequalities Done on board in class.

Refer to notes.Graph each inequality on a number line. x > 6 x 6

x 6 x 6

Remember: a (closed circle) means the

number IS included in the graph

a (open circle) means the point is NOT included in the graph

Example 6: Write an Inequality

See example 6 on pg. 342 and notes forExamples (sorry, number lines are a

bear to make!!)

Your Turn!

Write an inequality: The 10km race time of 86 minutes was

at least twice as long as the winner’s time. 86 2w

Five times a number is less than 65

5n 65

Still your turn :o)

For the value given, state whether each inequality is true or false.

5k 35, k= 7

14 + n 23, n = 8

5(7) 3535 35FALSE

14 + 8 23 22 23 TRUE

And Again!

Graph the inequality on a number line.

n -3 d 5

Write an inequality for each graph: See the board.

Extra Practice is by the door on your way out!!

Make sure you keep the and straight when graphing and when interpreting graphs! Practice this!!