The first thing that he has to do is take that "minus" sign through the parentheses containing the second polynomial. Some students find it helpful to put a " 1 " in front of the parentheses, to help them keep track of the minus sign. Here's what the subtraction looks like, when working horizontally/
Start by finding the LCM of the coefficients of each polynomial:
Next, to find the least common multiple of each of the following terms, we need to take the absolute minimum we can of each term (, , and ). The largest term of is in the first polynomial, so we'll take exactly that for our term in the LCM, absolutely nothing more. Similarly, the largest term of in any of the three polynomials is (also in the first polynomial) and the largest term in any of the three polynomials is in the second polynomial. Thus, the LCM of all our polynomials is: