Can anyone clarify the following points regarding calculus. Please

1. Jul 4, 2008

superstonerman

Wassup peeps. Can anyone clarify the following points to make sure what I know about calculus is correct. Anyway:

1. A function is defined as the relationship between two variables usually x and y.

2. A differential of a function states the rate of change between these two variables. How the dependent variable changes in regard to changes in the independent variable. Therefore given a continuous function it is possible to differentiate this function to obtain a statement that describes the rate of change between the variables x and y. For example the differential of y=x^2 is y'=2x. Therefore 2x describes how the dependent variable y changes with regards to how the independent variable x changes.

3. This differential can also be seen as the slope of the tangent to a function.

5. The integral and therefore the process of integration is about finding the area under a curve. It has many other uses however this is how an integral can be defined.

3. Integration takes this rate of change, the derivative of the function and outlines a statement that describes the relationship between two variables, therefore a function. It can seen from this integration is the opposite of differentiation and vice-versa

4. Which is shown in the fundamental laws of calculus.

Please correct and explain anything you feel is incorrect. Thanks for your help

2. Jul 4, 2008

matt grime

2. A continuous function need not be differentiable.

3 (The second 3). How can it be seen from this? I don't see a justification there.

3. Jul 4, 2008

kkrizka

I would write that as:
1. A function is defined as the unique relationship between two variables usually x and y.

In other words, for each x there is only one y.

4. Jul 4, 2008

HallsofIvy

Staff Emeritus
A function is defined as a relationship between two quatitites so that if a is related to b, a is NOT related to any thing other than be. For example in y= x2 , y is a "function of x" but x is not a "function of y".

Given a differentiable function. A continuous function is not necessarily differentiable. For the example y= x2, saying "2x describes how the dependent variable y changes with regards to how the independent variable x changes" is too general. The rate at which y changes is specficially 2x times the rate at which x changes.

Be careful to distinguish between "derivative" and "differential". They are quite different and what you are talking about here is the "derivative", not the "differential".

Okay. I started to disagree until I saw your second sentence!