1. The problem statement, all variables and given/known data Okay, I have here the original equation that we start out with: f(x) = -2x + 4 2. Relevant equations I'm supposed to find the slope of that equation. Which is obvious, since it's -2. But I was supposed to show how it's consistent with the limit definition of slope, which originally looks like this: [f(x+h) - f(x)] / h The way they showed it, was by plugging in (x + h) into the x in -2x + 4. My question is, why exactly did they do that? Sorry if it's a stupid question, but it's been bugging me and I would like to know when to plug in the x + h, and when not to when determining slopes. Thanks in advance!