# Using 'nDeriv' on a TI-84 Plus

• October 6th 2008, 10:10 PM
Naur
Using 'nDeriv' on a TI-84 Plus
On my TI-84 Plus graphics calc, I've found there's a function called nDeriv, that can be used to find a derivative. It sounds useful, so how do I use it?
• October 6th 2008, 10:20 PM
Chris L T521
Quote:

Originally Posted by Naur
On my TI-84 Plus graphics calc, I've found there's a function called nDeriv, that can be used to find a derivative. It sounds useful, so how do I use it?

There may be other uses for this, but I know that it can compute the value of a derivative at a given x value.

So, for example, nDeriv(x^2+4x-3,x,2) will compute the derivative of $x^2+4x-3$ at $x=2$.

Others may want to add on to this. Also, why don't you look at the owner's manual for some more info?

--Chris
• October 6th 2008, 11:57 PM
Naur
I'm not sure where my manual is.
Why do you have to choose an x value? For example, the derivative of 2x = 2. How would you do that on a calculator?
It seems almost useless if you can only use it for a single point.

For example, the where I found out about it, I was reading the answer of a question. I had to sketch the derivative, and it said to use nDeriv in the calculator. But it seems it wouldn't help you sketch a graph, aside from delivering the derivative at certain points on the derivative function.
• October 7th 2008, 12:17 AM
earboth
Quote:

Originally Posted by Naur
I'm not sure where my manual is.
Why do you have to choose an x value? For example, the derivative of 2x = 2. How would you do that on a calculator?
It seems almost useless if you can only use it for a single point.

For example, the where I found out about it, I was reading the answer of a question. I had to sketch the derivative, and it said to use nDeriv in the calculator. But it seems it wouldn't help you sketch a graph, aside from delivering the derivative at certain points on the derivative function.

I've attached a screenshot to show you how to use nDeriv( with a TI84.

The TI84 calculates the value of the slope by iteration at a given x-value.
• October 7th 2008, 02:42 AM
SuperTyphoon
Go to Y=

Type in the function in Y1

Type in Y2: nDeriv(Y1,X,X)
*Y1 is found under "Vars" key under "Function"

It should draw the graph of the derivative.
• October 9th 2008, 02:44 AM
Naur
I had a practise exam, I used this quite a few times, even just finding the derivative at a certain point. Thanks.
Oh...so if I make the second value 'x', it will draw it...
Works perfectly, thanks very much :D