Simple calculus question

Baww, bad example. I meant more like. Uh. Say we have a function f(x) = x. Then lim(x -> a) should be f(a + epsilon) = f(a - epsilon) where you let epsilon go towards 0. Then that will never happen unless f(x) = k or that f(x) = k * sin or k * cosin and that x is an element in the value handed to sin or cosin.

And bahh. Infinity isn't a number.

Fine, negative infinity is a different concept. Yeesh.

I don't understand your first point. You don't define what "k" is and I don't know how f(x) can equal a sine or cosine function when you already said f(x) = x. o.O And I don't get what you're trying to say with the trig anyway.

Does this help?

In this case, the lim(x -> a) = 1, not 1.5. It doesn't matter what f(x) is at the point, it matters what it approaches.

Quite simply speaking, you can define the answer in terms of approach, or L'Hospital's rule. For general purposes and derivatives/integrals, if all approaches do not equal each other, the particular point in question is undefined. For example, tan(90 degrees) is undefined.

@ Morgana, I've only seen DNE in L'Hospital shyts, and nowhere else o.O

I agree with you... the function tan(90 degrees) is undefined, since the function has no value at that point. But the limit of tan(x) as x approaches 90 degrees is DNE. Does that help?



Also, srsly guys, it's DNE. o.O