1. Unit 2: Day 3
writing equations

2. Agenda
Warm-up
Homework check
Notes
Homework

3. Warm- Up Write and solve the expression:
A football team gains 10 yards but then loses 3 yards on the next play. What is the net yards?
The temperature falls 15 degrees then rises 18 degrees. What is the change in temperature?

4. Homework Check

5. Review Let n = 2.3, Evaluate the following: 1. -n + 8.9 2. n + -4.5

6. Review Write as an Exponent: Write an equation: w * w * w * w 3 * 3
3. “eight less than a number n is 23

7. Writing Equations! What is an Equation?
A mathematical sentence that uses an equal sign. (Just an expression with an equal sign)
Exs: y = 5 or = 9

8. Writing Equations
You must ALWAYS define your variables before you can write the equation:
How to define your variable:
______ represents __________
The variable What you are
you choose defining

9. Define Variables and Write an equation to model the situation
1. The total cost is the number of cans times $0.70
Have groups complete this slide. Walk around the room and have a group or two put their answers on the board. Have the remaining groups decide if the answers are correct.

10. In Groups:
2. The perimeter of a regular hexagon is 6 times the length of one side. 3. What is the number of slices of pizza left from an 8-slice pizza after you have eaten some slices?

11. P=6L  from # 2 in groups What is the P and L in this equation?
P is a variable that represents the perimeter
L is a variable that represents the length of one side.
What is the 6?
6 is the coefficient of the variable L.
P=6L is one answer to number 2 from the previous slide. Use this to discuss

12. In groups answer the question:
The length (L) of a rectangle is 8 in. and the width (w) is 3 in. Find the perimeter of the rectangle. Make sure you can explain (write out) how you find your answer!
Have different groups share how they get their answer!

13. Number of iPhones built
Define the variables and write an equation to model the relationship in the table
Number of Machines
Number of iPhones built 1 13 2 26 3 39 4 52

14. Practice:
Write an equation to show the total income from selling tickets to a school play for $5 each.
Write an equation for the data in the table:
Gallons Used 4 6 8 10
Miles Traveled 80
120
160
200

15. Real World Problem:
A neighborhood association turned a vacant lot into a pool. The pool is shaped like a trapezoid
Use the formula to find the area of the lot when h = 130ft,
b1 =100ft and b2 = 200 ft.

16. Real World Problem
Tennis shoes cost $ However, every time you buy an item there is always sells tax of 7% included in the final price. What is the total price you will have to pay for the shoes?
Use the formula: C=p+r*p where C is the total price, p is the original price, and r is the sales tax rate.

17. Create a word problem for the equation:
H = 5.5x

18. Homework
2.3