Can you point to a single reference anywhere dealing with calculus on the reals that is lazy enough to use infinity as "meh, I don't care if it's positive or ne

Can you point to a single reference anywhere dealing with calculus on the reals that is lazy enough to use infinity as "meh, I don't care if it's positive or negative infinity"? Even one? I've never seen it, and I've taught calculus to college students for nine years.