This section doesn't actually have many to do with the rest of this chapter, but since the subject required to be covered and it was a fairly short chapter it appeared like as good a place as any to put it.

Hence, let's begin with the following.  Let's assume that we desire to add the following two rational expressions.

8/(x+1) -5/(x-4) = 8 ( x - 4)/(x+1)(x+4) -5(x+1)/ (x+1)(x+4)

                        = 8x -32- (5x+5)/(x+1)(x-4)

                        = 3x-37/(x+1)(x-4)