# Algebra

posted by .

I am stumped by these two LCM questions for some reason.

Find The LCM for
#1
2(R-7) and 14(R-7)

#2
(1+4r), (1-16r^2), and (1-4r)

It seems like #1 is already at the LCM
and #2 would be (1+4r)(1-4r)
Am I even vaguely correct?

• Algebra -

As you probably know, if one number is a multiple of the other, the bigger number is the LCM of the two.

For #2, you are more than vaguely correct, but you do not appear to have any justification of your response.

You can confirm your thoughts by dividing the LCM by each of the three values. If they all divide without remainder, and there is no common factor between the quotients, the answer is correct.

For example,
If 60 is the LCM of 5,6,15, then
60/5=12 has no remainder
60/6=10 has no remainder
60/15=5 has no remainder.
However,
5,10 and 12 have a common factor of 2, so 60 is not the LCM, but 60/2=30 is!

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