Algebra LCD
posted by Clark .
Lowest common denominator of denominators (3x^4)27x^2 and (x^3)3x^2

First, fully factor both.
(3x^4)27x^2 = 3x^2(x^2  9)
= 3x^2*(x+3)(x3)
(x^3)3x^2 = x^2(x3)
The LCD is 3x^2*(x3)(x+3).
It is the product of all factors appearing in both expressions. Factors that appear in both only appear once in the LCD.