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What does: Find LCM of 4 and 12 useing prime factors mean?!

 Jun 6, 2015

Best Answer 

 #3
avatar+28132 
+10

LCM means Lowest Common Multiple

 

To find the LCM first find the prime factors of each number, then take the prime factors with the largest powers that occur and multiply them all together.  So:

 

Prime factors of 4:  22 

Prime factors of 12:  22*3

 

The highest power term with 2 is 22 and the highest power term with 3 is just 3, so we multiply 22*3 to get 12.

 

This means the LCM of 4 and 12 is 12 itself.

 

Let me do a different example: suppose we want the LCM of 9 and 12:

 

Prime factors of 9:  32

Prime factors of 12:  22*3

 

Now we take 22 and multiply by 32 to get 22*32 = 36

So 36 is the LCM of 9 and 12

.

 Jun 7, 2015
 #1
avatar+4691 
+5

LCM= Lowest common multiple

 

And you're finding the factors of 12 and 4 to do this.

You can present this as the tree form.

 

Using that information you can answer the question.

 

4 - lowest factor (not including 1) is 2

12 -lowest factor (not including 1) is 2

 

Thats the LCM of those two.

 Jun 6, 2015
 #2
avatar+4691 
+5

Note that Prime factors is only prime numbers.

 

E.g. 15 prime numbers are 15, 1, 3, 5

 

Prime factors of it . 5 is a prime number .  3 is a prime number . 1 is technically not a prime number and 15 isn't.

 Jun 6, 2015
 #3
avatar+28132 
+10
Best Answer

LCM means Lowest Common Multiple

 

To find the LCM first find the prime factors of each number, then take the prime factors with the largest powers that occur and multiply them all together.  So:

 

Prime factors of 4:  22 

Prime factors of 12:  22*3

 

The highest power term with 2 is 22 and the highest power term with 3 is just 3, so we multiply 22*3 to get 12.

 

This means the LCM of 4 and 12 is 12 itself.

 

Let me do a different example: suppose we want the LCM of 9 and 12:

 

Prime factors of 9:  32

Prime factors of 12:  22*3

 

Now we take 22 and multiply by 32 to get 22*32 = 36

So 36 is the LCM of 9 and 12

.

Alan Jun 7, 2015
 #4
avatar+100 
+5

Thank you all so much!! 

+Mathsgod1 +Alan   

 Jun 7, 2015

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