Derivative value of any expression at a point using Calculator App

 To find derivative value at a point with respect to variable X -

- Tap on the "Var" option and select ∂/∂X to find the 1st derivative (or ∂²/∂X to find the 2nd derivative).

- The app inputs the expression derv(1, , X) where the first parameter of derv is 1 for1st derivative and third parameter X specifies the variable. Input the expression whose derivative needs to be calculated at current value of X in 2nd parameter. A sample snapshot is shown below.

The above snapshot calculates derivate of expression X*X + 2X - 1 at specified value of X = 1

To find derivative at any other value of X, change the specified value of X.