Adding and Subtracting Fractions and

Mixed NumbersWhat we have to learn:

·How to add and subtract positive and negative fractions with like denominators·How to add and subtract positive and negative fractions with unlike denominators·How to add and subtract positive and negative mixed numbers with like denominators·How to add and subtract positive and negative mixed numbers with unlike denominators

Let's go! Next page......

·How to add and subtract positive and negative fractions with like denominators and variables

If we have time, we will learn:

·How to add and subtract positive and negative fractions with like denominators

Rule: If the denominators are the same, just add the numerators. Follow the adding rules for integers!!!

Example: 2 + 5 = 7 3 3 3

Example: -7 - -9 = -7 + +9 = 2 15 15 15 15 15

Try these:

1) 2 + -19 23 23

2) 6 - 15 47 47

3) -9 + -8 123 123

Press button for correct answers.

4) -7 + -4 22 22

REMEMBER TO SIMPLIFY!!!

REMEMBER YOUR ADDITION RULES: ADD THE OPPOSITE!!

·How to add and subtract positive and negative fractions with unlike

denominatorsRule: You must find a common denominator and make equivalent fractions. Then add and subtract the usual way. (best way: use the LCD)

Examples:

1) 12 + 4 25 5

2) 3 - 3 7 5

3) -6 + -4 11 6

32/25

-6/35

-40/33

(answers are under the bunny!)

How to add and subtract positive

and negative mixed numbers. Rule: Always change mixed numbers to improper fractions!!!!

This is a Mrs. Gelin rule. You actually can add without changing a mixed number, but it is easy to make errors. You can subtract without changing a mixed number, but the vast majority of students will make an error during subtraction.

You MUST change a mixed number to an improper fraction when multiplying and dividing, and it is MUCH easier to change it when adding and subtracting.

Therefore, it is a rule IN THIS CLASS that you MUST change mixed numbers to improper fractions when adding, subtracting, multiplying and dividing.Then, just follow the

regular fraction rules.Examples:

1) 2 1/3 + 4 1/5

= 7/3 + 21/5

= 35/15 + 63/15

= 98/152) 3 1/9 - 5 1/2

= 28/9 - 11/2

= 56/18 - 99/18

= 56/18 + (-99/18)

= -43/18

ADD & SUBTRACT:

MULTIPLY & DIVIDE:

CHANGE TO IMPROPER FRACTION

FIND COMMON DENOMINATOR

ADD AND SIMPLIFY.

PRACTICE:FRACTIONS:

PAGES 250-251 # 1, 4-7, 9-11

MIXED NUMBERS:PAGES 250-251#13-21, 32-33

How to add and subtract positive and negative fractions with like denominators and variables.Easy peasy--use the same rule as without

variables.Examples:

1) keep the denominator and add the numerators.

3 + -6 = -3x x x

2) Keep the denominator and add the numerators.x - 8 = x-

817 17 173) keep the denominators and add the

numerators.

2x + 4x = 6x 13 13 13

Try these:

1) 3x - -6 8 8

2) -3 + -9 y y

3) 2R - 9R 10 10

1) 3x + 6 / 8

2) -12/y

3) -7R/10

(answers are behind star)