Answer:
LCD = (x - 7)(x + 3)(x + 2)(x - 2)
Step-by-step explanation:
First, we factor each polynomial.
x^2 - 4x - 21 = (x - 7)(x + 3)
x^2 - 4 = (x + 2)(x - 2)
There are 4 different factors and none are in common, so the LCD is the product of all the factors.
LCD = (x - 7)(x + 3)(x + 2)(x - 2)
