Graphing and Writing Inequalities with One Variable DAY 9 Return to table of contents

When you need to use an inequality to solve a word problem, you may encounter one of the phrases below. Important Words Sample Sentence Equivalent Translation is more thanTrenton is more than 10 miles away. t > 10 is greater thanA is greater than B. A > B must exceedThe speed must exceed 25 mph. The speed is greater than 25 mph. s > 25

When you need to use an inequality to solve a word problem, you may encounter one of the phrases below. Important Words Sample Sentence EquivalentTranslation cannot exceedTime cannot exceed 60 minutes. Time must be less than or equal to 60 minutes. t < 60 is at mostAt most, 7 students were late for class. Seven or fewer students were late for class. n < 7 is at leastBob is at least 14 years old. Bob's age is greater than or equal to 14. B > 14

How are these inequalities read? > 3 Two plus two is greater than ≥ 4 Two plus two is greater than or equal to < 5 Two plus two is less than ≤ 5 Two plus two is less than or equal to ≤ 4 Two plus two is less than or equal to > 3 Two plus two is greater than or equal to 3

Writing inequalities Let's translate each statement into an inequality. x is less than is greater than or equal to y x < 10 words inequality statement translate to 20 > y

You try a few: is greater than a 2. b is less than or equal to is less than the product of f and The sum of t and 9 is greater than or equal to more than w is less than or equal to decreased by p is greater than or equal to 2 7. Fewer than 12 items 8. No more than 50 students 9. At least 275 people attended the play

Do you speak math? Change the following expressions from English into math. Double a number is at most four. Three plus a number is at least six. 2x ≤ x ≥ 6 Answer

Five less than a number is less than twice that number. The sum of two consecutive numbers is at least thirteen. Three times a number plus seven is at least nine. x - 5 < 2x x + (x + 1) ≥ 13 3x + 7 > 9 Answer

$ at least > An employee earns e A store's employees earn at least $7.50 per hour. Define a variable and write an inequality for the amount the employees may earn per hour. Let e represent an employee's wages.

Try this: The speed limit on a road is 55 miles per hour. Define a variable and write an inequality.

118You have $200 to spend on clothes. You already spent $140 and shirts cost $12. Which equation shows this scenario? A200 < 12x B200 12x C200 > 12x D200 12x ≤ ≥

119 A sea turtle can live up to 125 years. If one is already 37 years old, which scenario shows how many more years could it live? 125 < 37 + x x≤ A B C125 > 37 + x D x≥

120The width of a rectangle is 3 in longer than the length. The perimeter is no less than 25 inches. A4a + 6 < 25 B4a + 6  25 C4a + 6 > 25 D 4a + 6 ≥ 25 ≤

121The absolute value of the sum of two numbers is less than or equal to the sum of the absolute values of the same two numbers. A B C D

This would be read as the solution set is all numbers greater than or equal to negative 5. Solution Sets

Let's name the numbers that are solutions of the given inequality. r > 10 Which of the following are solutions? {5, 10, 15, 20} 5 > 10 is not true So, not a solution 10 > 10 is not true So, not a solution 15 > 10 is true So, 15 is a solution 20 > 10 is true So, 20 is a solution Answer: {15, 20} are solutions of the inequality r > 10

Let's try another one. 30 ≥ 4d; {3, 4, 5, 6, 7, 8} 30 ≥ 4d 30 ≥ (4)3 30 ≥ ≥ 4d 30 ≥ (4)4 30 ≥ ≥ 4d 30 ≥ (4)5 30 ≥ ≥ 4d 30 ≥ (4) 6 30 ≥ ≥ 4d 30 ≥ (4)7 30 ≥ ≥ 4d 30 ≥ (4)8 30 ≥ 32 click to reveal

Graphing Inequalities - The Circle

Graphing Inequalities - The Arrow The arrow should always point in the direction of those numbers who satisfy the inequality. *If the variable is on the left side of the inequality, then < and ≤ will show an arrow pointing left. *If the variable is on the left side of the inequality, then > and ≥ will show an arrow pointing right.

Notice that < and ≤ look like an arrow pointing left and that > and ≥ look like an arrow pointing right. But what if the variable isn't on the left? Do the opposite of where the inequality symbol points

INEQUALITY SYMBOLS DOT AND DIRECTION < >

What is the number in the inequality? What kind of circle should be used? In what direction does the line go? Graphing Inequalities

Step 1: Rewrite this as x < 5. Step 2: What kind of circle? Because it is less than, it does not include the number 5 and so it is an open circle Graphing Inequalities x is less than 5

Step 4: Draw a line, thicker than the horizontal line, from the dot to the arrow. This represents all of the numbers that fulfill the inequality. Step 3: Draw an arrow on the number line showing all possible solutions. Numbers greater than the variable, go to the right. Numbers less than the variable, go to the left x <

Step 1: Rewrite this as x ≤ 5. Step 2: What kind of circle? Because it is less than or equal to, it does include the number 5 and so it is a closed circle Graphing Inequalities x is less than or equal to 5

Step 4: Draw a line, thicker than the horizontal line, from the dot to the arrow. This represents all of the numbers that fulfill the inequality. Step 3: Draw an arrow on the number line showing all possible solutions. Numbers greater than the variable, go to the right. Numbers less than the variable, go to the left x ≤ 5

You try Graph the inequality x > 2 Graph the inequality -3 > x click 2 on the number line for answer click -3 on the number line for answer

Try these. Graph the inequalities. 1. x > x <

Try these. State the inequality shown

122 This solution set would be x > A True B False

Ax > 3 Bx < 3 C Dx > 3 State the inequality shown.

A13 < x B13 > x C D13 < x State the inequality shown.

Ax > -1 Bx < -1 C Dx > -1 State the inequality shown.

A-4 < x B-4 > x C-4 < x D-4 > x State the inequality shown.