1.4  Addition of Real Numbers     Homework: Odds 1-53

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DSPM 0800 Class Notes

Illustrating Addition on a Number Line:
Example:   3+2 = 5
Begin at the number 3. If the number being added is positive, move to the right. If the number being added is negative, move to the left.
Example:  3+(-5) = -2

For any
For                  
 

Rules For Addition:

1) SAME SIGNS:  Keep sign and add.

2) OPPOSITE SIGNS:  Keep sign of larger number and subtract.

Example: 13 + (-25)    Opposite signs
                 - (25-13)     Keep sign of larger number and subtract  
                 - 12

Example:  -14 + (-29)    Same signs
                  - (14 + 29)   Keep sign and add
                  - 43

Example:  112 + 39        Same signs
                 + (112 + 39)  Keep sign and add
                   151

*Notice: When adding several numbers, you can add from left to right  OR  you can add the positive numbers and add the negative numbers, then combine the two sums.

Applications:
Example: In a college football game, the quarterback attempted passes with the following results
                        1st pass – 13 yd. gain
                        2nd pass – Incomplete
                        3rd pass – 12 yd. loss
                        4th pass – 21 yd. gain
                        5th pass – 14 yd. loss
Find the total gain (or loss).