I am crafting materials for college students in my classes to address algebra misconceptions, and I need a simple set of vocabulary to distinguish between two things when performing complex substitutions:
When substituting one more complex sub-expression in for another equal complex sub-expression in an existing expression or an equation, I want some way to refer to each of these sub-expression using a single word, instead of saying awkward things over and over like "original sub-expression" and "new sub-expression" which are longer and somewhat ill-defined. I can invent my own vocabulary, but I'm thinking there must be some existing well-defined vocabulary for this in some branch of higher mathematics, or education, or some related field. I was hoping someone here might be able to help me figure out what terms might make the most sense to use here?
Thanks in advance for reading my post!