What is the least common multiple, LCM, of the two polynomials?
(x + 3) and (x2 - 9)

A.(x - 3)(x + 3)
B.(x + 3)
C.(x - 3)
D.3

Question

What is the least common multiple, LCM, of the two polynomials?
(x + 3) and (x2 - 9)

A.(x - 3)(x + 3)
B.(x + 3)
C.(x - 3)
D.3

kinggeorge · Answer

An easy way to do this, is to notice that the LCM of anything and $(x^2-9)$ must have an $x^n$ term where n is at least 2. Of the possible solutions, only A. $(x-3)(x+3)$ satisfies that. 

Thus, the answer must be A.

kinggeorge · Answer

If you want to check that is the correct LCM, first notice that $(x-3)(x+3)=(x^2-9)$ and that it has an $(x+3)$ term. Thus, it must be the LCM.