Transcript CA Math 3_6 Add and Sub unlike fractions
Adding and Subtracting Unlike Fractions
3.6
To add and subtract fractions with unlike denominators, first find a common denominator using one of these methods: Method 1 Find a common denominator by multiplying the two denominators.
Method 2 Find the least common denominator (LCD) of the denominators. (Cake Method)
Steps
• • • • Find LCD or CD Write equivalent fractions: Multiply the fraction by a value of 1 in order to get the LCD or CD Add or subtract the numerators Reduce
Write in Simplest form: 5 9 1 6 • LCD: 18 • Rename Fractions: 9 5 2 2 10 18 6 3 • Add the numerators: 10 3 18 18 18 3 18 7 18
Write the answer in simplest form.
5 5 4 2 5 4 Find a common denominator: 4(5) = 20.
Multiply by fractions equal to 1.
15 20
+
23 20 8 20 1 3 20 Rewrite with common denominators.
Add numerators. Keep the denominator.
Rewrite as a mixed number.
Write in Simplest Form:
2 2 5 5 6 35 6 2 1 4 70 9 4 27 12 12 3 3 97 12 1 8 12
Find the perimeter of the figure below.
2 3 1 2
First
, work with 1 4
+
1 2 3 1 1 2 4 1 2 6 3 3 4 the fractions.
Then
, work with the whole numbers.
Last
, simplify.
1 8 12 1 3 12 2 6 12 4 17 12 4 1 5 12 5 5 12
1 2 Vickie has cups of shredded cheese to put in her 3 enchilada casserole and ¾ cup of cheese for the top. If she has 3 cups of cheese in all, how much cheese will 3 3 1 2 3 5 3 she have left? 3 4 3 4 3 4 4 5 3 3 3 3 4 3 20 12 9 12 3 29 12 3 12 12 36 29 12 29 12 12 7 12
Homework:
• Page 129 (14-46) even