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3-1 DAY 1 INEQUALITES & THEIR GRAPHS. Caffey MHS Algebra I October 2012.
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3-1 DAY 1INEQUALITES & THEIR GRAPHS Caffey MHS Algebra I October 2012
By law, the height of a newly construct4ed building in Washington DC can be no greater than the width of the adjacent street plus 20 ft. Pennsylvania street, is the widest street in DC. What is the maximum allowable height of a new building?
PROBLEM #1 Writing Inequalities HOW DO YOU WRITE AN INEQUALITY? What inequality represents the verbal expression? All real numbers x less than or equal to -7 x -7 EX2:6 less than a number k is greater than 13 k-6 > 13
Student’s Try: • All real numbers p greater than or equal to 1.5 • The sum of t and 7 is less than -3
VOCABULARY • SOLUTION OF AN INEQUALITY – any number that makes the inequality true
PROBLEM #2 Identifying Solutions by Evaluating Is the number a solution of 2x + 1 > -3? The number is -3 Step 1 Write the inequality 2x + 1 > -3 Step 2 Substitute the given 2(-3) + 1 > -3 number for x Step 3 Simplify -6 + 1 > -3 Step 4 Compare -5 > -3 No, Since -5 is not greater than -3, -3 is not a solution
TRY THIS: Consider the numbers -1, 0, 1, and 3. Which are solutions of 13 – 7y 6?
Determine whether each number is a solution of the given inequality • -2p – 3 -1 a.-2 b. 2 c. 4 a) -2 (-2) – 3 -1 4 – 3 -1 1 -1 This is not true, so -2 is not a solution
PROBLEM #2 Identifying Solutions by Evaluating Is the number a solution of 2x + 1 > -3? The number is -1 Step 1 Write the inequality 2x + 1 > -3 Step 2 Substitute the given 2(-1) + 1 > -3 number for x Step 3 Simplify -2 + 1 > -3 Step 4 Compare -1 > -3 YES, since -1 is greater than -3, -1 IS a solution
HOMEWORK • PAGE 176 (7-10, 12 - 28 EVEN) • CLOSURE:How do you decide whether a number is a solution of an inequality? • What are 3 possible values for b that make the inequality b<-4 true?
3-1 Day 2 Inequalities & Their Graphs 2 3 4 5 6 7 8
Inequalities and their Graphs Objective: To write and graph simple inequalities with one variable
What is a good definition for Inequality? Inequalities and their Graphs An inequality is a statement that two expressions are not equal 2 3 4 5 6 7 8
Inequalities and their Graphs Terms you see and need to know to graph inequalities correctly < less than Notice open circles > greater than
Inequalities and their Graphs Terms you see and need to know to graph inequalities correctly ≤ less than or equal to ≥ greater than or equal to Notice colored in circles
Inequalities and their Graphs Let’s work a few together Notice: when variable is on left side, sign shows direction of solution 3
Inequalities and their Graphs Let’s work a few together Notice: when variable is on left side, sign shows direction of solution 7
Inequalities and their Graphs Let’s work a few together Notice: when variable is on left side, sign shows direction of solution Color in circle -2
Inequalities and their Graphs Let’s work a few together Notice: when variable is on left side, sign shows direction of solution 8 Color in circle
Graphing Inequalities Excellent Job !!! Well Done
PROBLEM 3: Graphing an Inequality • What is the graph of ? • ***Re-Write the problem so the variable is on the left*** Step1: Since a can be equal to 2, draw a circle at 2 Step 2: the numbers less than 2 are to the left of 2 on the number line, so shade to the left of 2
PROBLEM #4: Writing an Inequality from a Graph • L:\ALGEBRA - MHS (SANDISK)\CH 3 SOLVING INEQUALITIES (SANDISK)\3-1 DAY 2A Pearson Prentice Hall Mathematics Video.mht
What inequality represents the graph? • Look at the arrow – Decide if the solution is greater than or less than the endpoint • Look at the endpoint – Decide if “EQUAL TO” is included in the solution.
STUDENTS TRY: 1 2
CLOSURE • What inequality describes the situation?
CLOSURE • What inequality describes the situation?
HOMEWORK • PAGE 181 (#5-30 ALL)