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

Answer 1

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.

Answer 2

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.