Adding Fractions

Adding Fractions

Find Least Common Multiple

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Add Numerators Keep Denominator

Rewrite fractions with common denominator

Similarly we have:

1)Before you can add two fractions you have to find their common denominator. The smallest common denominator is called the Least Common Multiple and LCM for short. Here we have the prime factorization of 4 and 5 and the LCM:

3) Only when both fractions have the same denominator we can go ahead and add them by adding the numerators on top and keeping the same common denominator on bottom.

Video

2)Now we must convert our fourths and fifths into twentieths, we will use a usefull form of 1. For example the 4 in the fraction 1/4 needs to become a 20. We will multiply the bottom 4 by a 5 and also multiply the top 1 by 5. Since we are multiplying top and bottom by 5/5 we are essentially multiplying by a 1.

References

Martin Cardenas

Adding Fractions with unlike denominators. (n.d.). Retrieved from YouTube Kahn Academy: https://www.youtube.com/watch?v=OVMceVL_CEQStapel, E. (n.d.). Fractions Review: Adding and Subtracting Fractions. Retrieved 10 28, 2014, from Purplemath: http://www.purplemath.com/modules/fraction4.htm (Adding Fractions with unlike denominators)

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