what is the LCM of 4 and 7?
回答 (8)
2010-01-13 11:21 am
✔ 最佳答案
4 = 2 x 2 7 = ...........7
------------------------
...= 2 x 2 x 7
...= 28
2010-01-13 6:13 pm
28
2010-01-13 6:34 pm
To find the LCM of any 2 numbers, you have to find the prime factors of each of the numbers first.
4 = 2 * 2 = 2^2
7 = 7^1
Then for each occurring prime factor, take the one from whatever number it has the highest exponent and multiply them.
In this example, the LCM of 4 and 7 is 2^2 * 7^1 = 28
Another example to make it a bit clearer:
We want to calculate the LCM of 18 and 60
18 = 2 * 9 = 2^1 * 3^2
60 = 4 * 15 = 4 * 3 * 5 = 2^2 * 3^1 * 5^1
For primefactor 2, 2^2 is highest occurrence
For primefactor 3, 3^2 is highest occurrence
For primefactor 5, 5^1 is highest occurrence
So the LCM is 2^2 * 3^2 * 5^1 = 4 * 9 * 5 =180
4 = 2 * 2 = 2^2
7 = 7^1
Then for each occurring prime factor, take the one from whatever number it has the highest exponent and multiply them.
In this example, the LCM of 4 and 7 is 2^2 * 7^1 = 28
Another example to make it a bit clearer:
We want to calculate the LCM of 18 and 60
18 = 2 * 9 = 2^1 * 3^2
60 = 4 * 15 = 4 * 3 * 5 = 2^2 * 3^1 * 5^1
For primefactor 2, 2^2 is highest occurrence
For primefactor 3, 3^2 is highest occurrence
For primefactor 5, 5^1 is highest occurrence
So the LCM is 2^2 * 3^2 * 5^1 = 4 * 9 * 5 =180
2010-01-13 6:22 pm
LCM of 4 and 7 :-
4=2*2
7=1*7
therefore, LCM =2*2*1*7=28
4=2*2
7=1*7
therefore, LCM =2*2*1*7=28
2010-01-13 6:19 pm
4 times 7. you get 28
2010-01-13 6:18 pm
4 can be decomposed as 2*2
7 is a prime
so having no primes in common in 4 and 7 The LCM is their product 4*7=28
7 is a prime
so having no primes in common in 4 and 7 The LCM is their product 4*7=28
2010-01-13 6:17 pm
4*7 = 28
2010-01-13 6:16 pm
28
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