SOLUTION: Find the LCD of; 3/a, 3/b, 1/5, I thought that 5 was the LCD but it wasnt, could someone please explain why?

Algebra ->  Numeric Fractions Calculators, Lesson and Practice -> SOLUTION: Find the LCD of; 3/a, 3/b, 1/5, I thought that 5 was the LCD but it wasnt, could someone please explain why?      Log On


   

Question 147360: Find the LCD of; 3/a, 3/b, 1/5, I thought that 5 was the LCD but it wasnt, could someone please explain why?
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
First find the GCF between "a" and "b". The GCF is 1.

Now multiply "a" and "b" to get ab. Now divide the product ab by the GCF 1 to get ab%2F1=ab. So the LCM of the first two terms "a" and "b" is ab


So now the list of denominators updates from "a","b", and 5 to ab and 5



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Use the same steps as described above to find the LCD of the numbers ab and 5 to get 5ab. So the LCD is 5ab.




Think about it this way: if you multiplied every term by the LCD, then every denominator should cancel out and go away. If you multiply the supposed LCD of 5 by 3%2Fa, does the denominator cancel out? No it does not. However, multiplying the true LCD 5ab by 3%2Fa cancels out the denominator.