# Thread: why derivatives? What does it mean?

1. Hey guys.

Can anyone explain to me why we use derivates, what does it give us ? I dont want to hear definition words. Explain to me like you would explain to a child. Simply and straightforward. No fancy words.
What does the definition of the derivative tell us? Why must we derive a funtion in such way to get the derivative? I understand that "that is what the formula saids". But im not here to only go by the formula. I want to understand. Everything has its reason and im looking for the explanation. Just explain it as simply as possibly.

Thank you

2. Originally Posted by anbak89
Hey guys.

Can anyone explain to me why we use derivates, what does it give us ? I dont want to hear definition words. Explain to me like you would explain to a child. Simply and straightforward. No fancy words.
What does the definition of the derivative tell us? Why must we derive a funtion in such way to get the derivative? I understand that "that is what the formula saids". But im not here to only go by the formula. I want to understand. Everything has its reason and im looking for the explanation. Just explain it as simply as possibly.

Thank you
Let's do it by an example: a car travels the distance in a time interval . The car speed is:

, agreed?

When you take the above to the limit when you still get the speed, the INSTANTANEOUS speed of the car. This limit, is nothing else but the derivative of with respect to .

3. Originally Posted by AndrewC
Let's do it by an example: a car travels the distance in a time interval . The car speed is:

, agreed?

When you take the above to the limit when you still get the speed, the INSTANTANEOUS speed of the car. This limit, is nothing else but the derivative of with respect to .
Ok i understand your example, but I have a question.
Why do we want 'when limit goes to zero'? ( im on my phone and i cant do the symbol). What does it give us? What is its purpose?

Thank you for your time

4. Originally Posted by anbak89
Ok i understand your example, but I have a question.
Why do we want 'when limit goes to zero'? ( im on my phone and i cant do the symbol). What does it give us? What is its purpose?

Thank you for your time
The smaller the interval, the closer to the INSTANTANEOUS speed.

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