4-5 SOLVING INEQUALITIES USING ADDITION AND SUBTRACTION MISS BATTAGLIA – ALGEBRA 1 CP OBJECTIVE: USE ADDITION AND SUBTRACTION TO SOLVE ONE-STEP INEQUALITIES; USE INEQUALITIES TO MODEL REAL-WORLD PROBLEMS.

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. 12 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)1b) – 7.3c) 9.00 d) 0e) 3

GRAPHING INEQUALITIES x < 4 An open dot means 5 is not a solution. x < 4 A closed dot means 5 is a solution.

GRAPH x > -1 x > -1

EQUIVALENT INEQUALITIES Equivalent Inequalities have the same set of solutions. -4 < < < 3

PROPERTIES OF INEQUALITY Addition Property of Inequality For any numbers a, b, and c, if a > b then a + c > b + c For any numbers a, b, and c, if a < b then a + c < b + c Subtraction Property of Inequality For any numbers a, b, and c, if a > b then a - c > b - c For 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 $ 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