1. 1-4 adding and subtracting integers
Objective: add and subtract with integers and decimals, find absolute value, and evaluate expressions.
Ms. Battaglia – algebra 1 CP

2. Warm up
Simplify.

3. Example…
You’re at the supermarket and have $4.25 in your pocket. The groceries you buy cost $3.12. How much money do you have left? The groceries you want to buy cost $5.63. How much money do you owe?

4. Adding integers and decimals
A number line can help you see the relationship between numbers.
Opposites - same distance from zero on the number line.
Integers - whole numbers and their opposites.
What is the opposite of 3? -5? -100? 0?
Name the 2 integers that are a distance of 7 unites from 0.

5. The sum of a number and its opposite, or additive inverse, is zero.
definition
The sum of a number and its opposite, or additive inverse, is zero.

6. example
On two plays, a football team gains 2 yd and then loses 7 yd. What is the result of the two plays?

7. Addition rules…
To add two numbers with the same sign, add their absolute values. The sum has the same sign as the numbers. Examples: = (- 3) + (- 5) = To add two numbers with different signs, find the difference between their absolute values. The sum has the same sign as the number with the greater absolute value. Examples: = ( 3) + (- 5) =

8. Find each sum.
– 6 + 4
b) ( - 8)
c) 4 + (- 6)
d) 9 + (- 3)

9. Absolute value
The absolute value of a number is its distance from zero on a number line. Using symbols, you write the “absolute value of – 6” as |- 6|

10. example
Find the absolute value.
|- 12|
| 3.5|
|-5 + 3|

11. Examples
Evaluate each expression for n = 3.5 a) n b) – n

12. To subtract a number, add its opposite. Example: 3 – 5 =
Subtraction rule…
To subtract a number, add its opposite. Example: 3 – 5 =

13. example
Find each difference.
- 6 – 2
8 – ( - 1)
3 - 13

14. classwork
P #6bd, 11, 12cd, 15bcd, 16, 17

15. homework
P #3-7 odd, 8,10,12,29,30, 35 QUIZ IN 2 DAYS!