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anonymous
 5 years ago
When adding fractions, and you have to find the lowest common denominator. How do you know when to change the numerator? I am really confused!!!!
anonymous
 5 years ago
When adding fractions, and you have to find the lowest common denominator. How do you know when to change the numerator? I am really confused!!!!

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radar
 5 years ago
Best ResponseYou've already chosen the best response.0What ever you do to the denominator you do to the numerator otherwise you change the value of the fraction. If you multiply the denominator by 2 then multiply the numerator.\[1/3 + 3/4=\] What is the smallest number that both 3 and 4 will divide into with out a remainder (LCM). In this the LCM is 12 now examine the first fraction, its denominator is 3. What must 3 be multiplied with to equal 12? Your answer is 4. So if I multiply the denominator by 4 I MUST multiply the numerator by 4. The first fraction becomes 4/12. Treat next one in a similar manner.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Okay, so the next fraction will be 3/12!!!!!

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Okay, so what if i had a question like 1/4 + 3/10 + 2/5.The LCD is 20 right

idily101
 5 years ago
Best ResponseYou've already chosen the best response.01/4 would be 1/5 3/10 would be 6/20 and 2/5 would be 8/20

idily101
 5 years ago
Best ResponseYou've already chosen the best response.0do ypu understand how I got those fractions

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0How would 3/10 be 6/20 and 3x6 is 18??? I dont understand!!!

radar
 5 years ago
Best ResponseYou've already chosen the best response.0No the next fraction in y example was 3/4 we had already decided that 12 would be the LCD for those two fractions. You then multiplied the denominator by 3 and you got your 12.......But you failed to multiply the numerator by 3 !!!!! Remember what you do to the denominator you MUST do to the numerator. Multiplying it by 3 gives you 9/12 not what you got of 3/12 3/12 reduces to 1/4 not 3/4. Look at 9/12 it will reduce to 3/4, see you did not change the value, only the appearance!

radar
 5 years ago
Best ResponseYou've already chosen the best response.0Khiyah, take a breath and lets do your example. 1/4+ 3/10+2/5. Your choice of 20 was very good, it is the LCM. Convert your fractions with a denominator of 20 WITHOUT CHANGING THEIR VALUE. 1/4: To get a value of 20 I must multiply denominator by 5, what must I multiply the numerator by 5. 1/4=5/20 3/10 a 2 is used to get 20 use the 2 for the numertator also. 3/10 = 6/20. Do you get the procedure then you should get 8/20 for the last fraction. Please note we did not change the value of the fraction.
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