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

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

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

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)

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

2.3 – Subtraction of Real Numbers Example 2 Evaluate the expression 10 – 5 + 14 – (-18)

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.

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

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

2.3 – Subtraction of Real Numbers HOMEWORK Page 82 #16 – 50 even