Math 6A, Lesson 7, Fall 2020, 11/01/2020

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1. Quiz on negative number and addition of integers

2. Subtraction of integers:.subtraction is the reverse process of addition. Using a number line:

  • Subtraction of a positive number is taken as a movement to the LEFT of the number line
  • Subtraction of a negative number is taken as a movement to the RIGHT of the number line

(-3)  – 4

2 –  3

(-1) –  (-3)

2 –  (-5)

0 – (-4)

3. Rule for subtraction: to subtract integers, we change the sign of the integer being subtracted and add them together according to the rule for addition of integers.

For any integers a, and,b,

a – b = a + (-b)

4. Absolute value of the difference:

For any integers a, and,b,

|a – b| = |b – a|

5. Home Work:

  • Handout: two pages
  • Workbook:
    • page 8: 7
    • page 9: 17
    • page 10: 20