The dy/dx command finds a numeric derivative, which approximates the first derivative of an expression with respect to the x variable at the trace cursor location while viewing a graph.
While viewing the graph of a function, press to view the MATH functions.
If more than one function is graphed, use to select the desired curve and then use to trace the curve to the point for which the value of the derivative is needed.
Note: If the cursor cannot be placed close enough to the desired point, use the ZOOM feature and repeat the process.
Pressing will display the value (or approximate value) of dy/dx at the point.