# Thread: Using 'nDeriv' on a TI-84 Plus

1. ## 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?

2. 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

3. 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.

4. 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.

5. 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.

6. 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