Difference between Continuity and Derivatives.

In summary, continuity and differentiability are two different concepts that involve finding limits of a function. While a continuous function may have a limit at a point, it does not necessarily mean that it is differentiable at that point. Additionally, a function can be continuous at a point but not differentiable at that same point. It is important to consider the specific limits used in the definitions of continuity and differentiability when evaluating a function.
  • #1
cjaylee
7
0
Hey. I am quite confused by continuity and derivatives. Both are finding the limits of a particular function as x approaches a. Then why is it that a graph that is continuous cannot be differentiable? If it is continuous, it means that the limit exists and so, it should be differentiable right?
 
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  • #2
If p is three, does that mean q has to be three as well?

The limits used in the definitions of continuity and differentiability of a function f are different limits.
 
  • #3
For example, a function with a "point" (f(x)=|x| has a point at x=0) can be continuous but not differentiable since the derivative is different on either side of the point.
 
  • #4
cjaylee said:
Hey. I am quite confused by continuity and derivatives. Both are finding the limits of a particular function as x approaches a. Then why is it that a graph that is continuous cannot be differentiable? If it is continuous, it means that the limit exists and so, it should be differentiable right?
What "limit exists"? The limit you look at to determine if f(x) is continuous at x= a, is [itex]\lim_{x\to a} f(x)[/itex] while the limit you look at to determine if f(x) is differentiable at x= a is [itex]\lim_{h\to a} (f(a+h)- f(a))/h[/itex]. It is easy to show that if a function is differentiable at x= a, it must be continuous but the other way is not true.
 

What is the definition of continuity?

Continuity is a property of a function where the output values change smoothly as the input values change. In other words, there are no sudden jumps or breaks in the graph of the function.

What is the definition of a derivative?

A derivative is a measure of how a function changes as its input values change. It represents the slope of the tangent line at a specific point on the graph of the function.

What is the main difference between continuity and derivatives?

The main difference between continuity and derivatives is that continuity is a property of the function as a whole, while a derivative is a property of a specific point on the function.

How are continuity and derivatives related?

Continuity is a necessary condition for a function to have a derivative at a specific point. In other words, if a function is not continuous at a certain point, it cannot have a derivative at that point.

Can a function be continuous but not differentiable?

Yes, it is possible for a function to be continuous at a certain point but not have a derivative at that point. This usually occurs when the function has a sharp turn or corner at that point, which makes it impossible for a tangent line to be drawn.

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