1. Chapter 2 – Properties of Real Numbers
2.3 – Subtraction of Real Numbers

2. 2.3 – Subtraction of Real Numbers
Today we will be learning how to:
Subtract real numbers using the subtraction rule
Using subtraction of real numbers to solve real-life problems

3. 2.3 – Subtraction of Real Numbers
Some addition expressions can be evaluated using subtraction.
ADDITION PROBLEM
EQUIVALENT SUBTRACTION PROBLEM
5 + (-3) = 2
5 – 3 = 2
9 + (-6) = 3
9 – 6 = 3

4. 2.3 – Subtraction of Real Numbers
Adding the opposite of a number is equivalent to subtracting the number.
SUBTRACT RULE
To subtract b from a, add the opposite of b to a
a – b = a + (-b)
The result is the difference of a and b
Example: 6 – 4 = 6 + (-4)

5. 2.3 – Subtraction of Real Numbers
Example 1
Find the difference
-6 – 3
1/2 – 2/3
-15 – (-16)
-3 – 6

6. 2.3 – Subtraction of Real Numbers
Look at the first and fourth example.
In addition, we have the commutative property.
In subtraction, the order in which we subtract matters.

7. 2.3 – Subtraction of Real Numbers
Example 2
Evaluate the expression 10 – – (-18)

8. 2.3 – Subtraction of Real Numbers
When an expression is written as a sum, the parts that are added are the TERMS of the expression. For example, you can write the expression 8 – y as 8 + (-y). The terms are 8 and –y.

9. 2.3 – Subtraction of Real Numbers
Example 3
Find the terms of 3x – 5.

10. 2.3 – Subtraction of Real Numbers
Example 4
Evaluate the function y = -x – 7 for these values of x: -2, -1, 0, 1. Organize your results in a table & describe the pattern.
Input
Function
Output
x = -2
y = -(-2) - 7 -5
x = -1
x = 0
x = 1

11. 2.3 – Subtraction of Real Numbers
HOMEWORK
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