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Infinity
Mathematics uses the concept of infinity. It is written as ∞ for infinitely large and as Δx for infinitely small. But beware, for it are not numbers. You can perform calculations with it. If only you know what you are doing, because there are sometimes really surprises.
Infinitely large
We must always take care that ∞ has no fixed value, so
This works the same way for every number, also for very large ones. And even for
You can perform subtractions
That works for every number, however
= ?
Infinitely small
We take care, that Δx→0, so
as Δx is neglectable. But here again you see