Algebra I

Real life application

Solving linear systems with substitution

Example

You save $120 and save $8 per week. Your friend has $180 and saves $3 per week. After how many weeks will each of you have saved the same amount of money?

Example

• Last year you mowed grass and shoveled snow for 12 households. You earned $210 per household mowing for the entire season and $160 per household shoveling for the entire season. If you earned a total of $ 2,120 last year, how many households did you mow and shovel for?

Example 1:

In one day the National Civil Rights Museum in Memphis, Tennessee, collected $1590 from 321 people admitted to the museum. The price of each adult admission is $6. People with the ages of 4-17 pay the child admission, $4. Estimate how many adults and how many children were admitted that day.

Example 2:

An office supply company sells two types of fax machines. They charge $150 for one of the machines and $225 for the other. If the company sold 22 fax machines for a total of $3900 last month, how many of each type were sold?

Example 3 (matching activity)

• The Sluggers go out for pizza after a game. Five large pizzas plus three medium pizzas together have 110 slices. Two large pizzas plus nine medium pizzas have 122 slices how many slices are in each size?

Assignment

Page 409: # 42 & 44

Assignment

Page 409: # 42 & 44

Bell ringer 1/14/20111) Write an equation and solve for x if the

area of this rectangle is 133 square units.

2) Logan is thinking of a number. Three times the sum of the number and ten is the same as eight times the number. What is Logan’s number?

7

3x – 2

Algebra I

Real life application

Solving linear systems with Elimination

Algebra’s Cool DVD notesElimination Method:

•Make sure the equations have like terms aligned in columns.

•Multiply one or both equations by different numbers to eliminate a variable.

•Make the coefficients of either x or y opposites.

•Add the equations to eliminate on of the variables.

•Solve for the remaining variable.

• Substitute that value into either of the original equations.

• Solve for the other variable.

• Check the solution by making sure that the ordered pair satisfies both equations in the system.

Page 188• If a system of equations is solved by

elimination and the result is a false statement containing no variables, the system of equations has no solution.

• If a system of equations is solved by elimination and the result is a true statement containing no variables, the system of equations has an infinite number of solutions.

Page 193 in Packet

1) x + y = 15

3x – y =1

Page 193 in Packet

7) 3a + 5b = 114a – 3b = 5

Example 1

The senior class sold 173 tickets to the Christmas play. Adult tickets cost $6.25, and children’s tickets cost $3.75. If the senior class earned $858.75, how many of each kind of ticket was sold?

Example 2

• The perimeter of a rectangle is 30m. The length is twice the width. Find the dimensions.

Assignment

Workbook

Page 370 # 11-13 and 20, 22

Bell ringer 01/28/11

1) What percent of 50 is 75?

2) In an illustration of a car, the length of the car is 3 inches. The actual length of the car is 10.5 feet. What is the scale of the drawing?

3) Find the sum of the measures of the interior angles

of a 21-gon.

4) Classify the polygon & determine whether it is regular or not.

a) b) c)

Real world system of inequalities

Example 1

You are planning what to do after school. You can spend at most 6 hours daily playing basketball. You must spend at least 1 ½ hours on homework. What is a graph showing how you can spend your time?

Example 2

Suppose you have a job mowing lawns that pays $12 per hour. You also have a job at a clothing store that pays $10 per hour. You need to earn at least $350 per week, but you can work no more than 35 hours per week. You must work a minimum of 10 hours per week at the clothing store. What is a graph showing how many hours per week you can work at each job?