4-5 S

OLVIN

G INEQUALIT

IES

USING A

DDITIO

N AND

SUBTRACTI

ON

MI S

S B

AT T A

GL I A

– A

L GE

BR

A 1

CP

OB

J EC

TI V

E:

US

E A

DD

I TI O

N A

ND

SU

BT

RA

CT

I ON

TO

SO

LVE

ON

E- S

TE

P I

NE

QU

AL I T

I ES

; U

SE

I NE

QU

AL I T

I ES

TO

MO

DE

L RE

AL - W

OR

L D

PR

OB

L EM

S.

WARM UP

Jackie has $3.50 in quarters and nickels. If she has two more quarters than nickels, how many quarters does Jackie have?

WORK WITH A PARTNER

Define a variable and write an equality for each sign.1 2

3

WORK WITH A PARTNER

Define a variable and write an equality for each situation.

1) Persons under 17 are not admitted.

2) Visibility at the airport is less than 2 miles.

3) You must be more than 36 in. tall to ride an amusement park ride.

SOLUTION OF THE INEQUALITY

Any value of the variable that makes the inequality true is called a solution of the inequality.

Tell whether each number is a solution of x < 3.

a) 1 b) – 7.3 c) 9.00

d) 0 e) 3

GRAPHING INEQUALITIES

x < 4An open dot means 5 is not a solution.

x < 4A closed dot means 5 is a solution.

GRAPH

x > -1

x > -1

EQUIVALENT INEQUALITIES

Equivalent Inequalities have the same set of solutions.

-4 < 1

-4 + 2 < 1 + 2

-2 < 3

PROPERTIES OF INEQUALITYAddition Property of InequalityFor any numbers a, b, and c, if a > b then a + c > b + cFor any numbers a, b, and c, if a < b then a + c < b + c

Subtraction Property of InequalityFor any numbers a, b, and c, if a > b then a - c > b - cFor any numbers a, b, and c, if a < b then a - c < b - c

GRAPH THE SOLUTION ON A NUMBER LINE.

x – 3 < 5

GRAPH THE SOLUTION ON A NUMBER LINE.

w + 2 > -1

GRAPH THE SOLUTION ON A NUMBER LINE.

5.7 > k – 3.1

EXAMPLE

Your bank offers free checking for accounts with a balance of at least $500. Suppose you have a balance of $516.46 and you write the check below. How much must you deposit to avoid being charged a service fee?

HOMEWORK

Pg 182 #1-6, 8, 10, 12, 17,18, 29–35 odd