Warm – up

Toya is training for a triathlon and wants to bike and run on the same day. She has less than 3 hours to spend on her workouts. 1.What inequality represents the time Toya has to bike and run?2.What is the graph of the solutions?

Answer

b + r < 3

-2 -1 1 2 3 4 5

-2

-1

1

2

3

4

5

Questions over hw?

CCGPS Coordinate AlgebraDay 23 (9-13-12)

UNIT QUESTION: How do I justify and solve the solution to a system of equations or inequalities?Standard: MCC9-12.A.REI.1, 3, 5, 6, and 12

Today’s Question:How do I find the solutions to a system of linear inequalities graphically?Standard: MCC9-12.A.REI.12

SOLVING SYSTEMS SOLVING SYSTEMS OF LINEAR OF LINEAR

INEQUALITIES IN INEQUALITIES IN TWO VARIABLESTWO VARIABLES

Coordinate Plane

System of System of InequalitiesInequalitiesTwo or more inequalities in the same variables that work together

Solution to a System of Linear Solution to a System of Linear InequalitiesInequalities

The intersection of the half planes of the inequalities.

Look for the area where the shading overlaps. This is the solution.

Steps for Graphing Steps for Graphing InequalitiesInequalities

1.1. Graph the lines and appropriate shading for Graph the lines and appropriate shading for each inequality on the same coordinate each inequality on the same coordinate plane.plane.

2.2. Be sure to pay attention to whether the Be sure to pay attention to whether the lines are dotted or solid.lines are dotted or solid.

3.3. The solution is the section where all the The solution is the section where all the shadings overlap.shadings overlap.

Sometimes it helps to use different color Sometimes it helps to use different color pencils for each line and shaded region. It pencils for each line and shaded region. It makes it easier to determine the makes it easier to determine the overlapped shaded regions.overlapped shaded regions.

Ex.1

5

2 4 4

x y

x y

Ex. 2

2

2

y x

x

Ex. 3

It takes 2 hours to make the blade of a figure skate. It takes 3 hours to make the blade of a hockey skate. There is a maximum of 40 hours per week in which the blades can be made for both types of skates.

It takes 3 hours to make the boot of a figure skate. It takes 1 hour to make the boot for a hockey skate. There is a maximum of 20 hours per week in which boots can be made for both types of skates.

Ex. 3

1. What is the inequality that represents the time it takes to make the blades of the two different types of skates?

2. What is the inequality that represents the amount of time it takes to make the boots of the two different skates?

Ex. 3

Graph and consider some constraints to the problem.

What is the solution of all possible combinations of figure skates and hockey skates that can be produced given the constraints of this situation?

Ex. 3’s Solution with constraints

-8 -4 4 8 12 16 20 24

-10-8-6-4-2

2468101214161820

Ex. 4

Which system of inequalities represents the graph below?

Ex. 5

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