1 / 8

80 likes | 196 Vues

Adding Fractions Absent copy 12/6,7. 1st Method to adding fractions. Cross Multiply both denominators in order to get a common denominator. (small numbers) 3 + 3 5 4 Multiply by 4 to 3/5 4 • 3 + 3 • 5 Multiply by 5 to 3/4

Télécharger la présentation
## Adding Fractions Absent copy 12/6,7

**An Image/Link below is provided (as is) to download presentation**
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.
Content is provided to you AS IS for your information and personal use only.
Download presentation by click this link.
While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

**1st Method to adding fractions**Cross Multiply both denominators in order to get a common denominator. (small numbers) 3 + 3 5 4 Multiply by 4 to 3/54 • 3 + 3 • 5Multiply by 5 to 3/4 4 • 5 + 4 • 5 12 + 15 20 is the common denominator 20 20 Add the numerators12 + 15 = 27 = 1 7/20 20 20**Example 1**• Solve: write answer in simplest form 1 + 2 2 5 5 · 1 + 2 · 2 5 · 2 5 · 2 5 + 4 1010 5 + 4 = 9 Solution • Are these denominators both small numbers? • Yes they are both small. • What should we do to get denominators the same? • Because they are small we can cross multiply. • After we cross multiply to get the denominators the same then what? • We add the numerators and keep the denominator • Do we have to reduce this fraction? • No we don’t 9 10**Method 3 to adding fractions**We can use prime factorization to find the common denominator by multiplying the highest number of factors in each denominator. 1 + 5 8 12 Factor each denominator 8 12 2 • 2 • 2 3 • 2 • 2 Multiply the highest # of factors2 • 2 • 2 • 3 = 24Denominator Multiply the right factor to get denominator3 • 1 + 5 • 2 3 • 8 12 • 2 Add the numerators3 + 10 = 13 2424**Example 2**• Solve: write answer in simplest form -5 + -68 72 90 3 · 3 · 2 · 2 · 2 3 · 3 · 2 · 5 3 · 3 · 2 · 2 · 2 · 5 = 360 5 · -5 + -68 · 4 5 · 72 90 · 4 -25 + -272 = -297 360 360 360 Solution • What do we do to find the common denominator by using prime factorization? • We factor each denominator. • What prime factors do we see the most of in each denominator? • There is three 2’s and two 3’s with denom72 and one 5 with denom. 90. • What do we do with those factors to find the common denominator? • We multiply the factors together. • What do we do to each fraction in order to get the common denominator? • We find the right factor that we can multiply each fraction with to get the common denominator of 360. • After we get a common denominator what do we do? • We add the numerators and keep the common denominator. Simplify if needed. -297 360**Example 3**• Evaluate the expression When a = 1 b = 1 4 3 a + b 1 + 1 4 3 3 · 1 + 1 · 4 3 4 3 4 3 + 4 = 7 12 12 12 Solution • What do we do first? • We substitute the fractions for the variables. • What method do you think would work the best in finding the common denom? • They are small numbers so we should cross multiply to find common denom. • What do you do first? • We cross multiply each fraction to the opposite fraction. • What do we do second? • We add up the numerators and keep the denominator. • What do we have to check before we are finished? • We should check to see if the fraction should be simplified. 7 12**Example 4**• Solve: write in simplest form. 9 + 1 14 77 2 · 7 7 · 11 2 · 7 · 11 = 154 11 · 9 + 1 · 14 11 · 14 77 · 14 99 + 14 = 113 154 154 154 Solution • What do we do to find the common denominator by using prime factorization? • We factor each denominator. • What prime factors do we see the most of in each denominator? • There is one 2 and one 7 with denom14 and one 11 with denom. 77. • What do we do with those factors to find the common denominator? • We multiply the factors together. • What do we do to each fraction in order to get the common denominator? • We find the right factor that we can multiply each fraction with to get the common denominator of 360. • After we get a common denominator what do we do? • We add the numerators and keep the common denominator. Simplify if needed. 113 154**Example 5**• Simplify: 8 + 2 a b b · 8 + 2 · a b a b a 8b + 2a ab Solution • What method do you think would work the best in finding the common denom? • To cross multiply • What do you do first? • Cross multiply the denominators • Can we add the numerator? Yes or No • What is the proper way to write the numerator? • In alphabetical order 2a + 8b ab

More Related