Power on your Nspire and press "Home," "7" and scroll down to select "Quadtratic Tangents" from within "My Documents." This is a sample problem on the Nspire.
Highlight "Point X" by scrolling to the right and selecting the highlighted point on the graph with the center button.
Press "2" and access "View," and press "6" to select "Points & Lines." This will display a line on your graph, after you enter in a numerical value.
Enter "2x" into the text area and press "Graph" to see the resulting line.
Evaluate the captured slope by going to "Page 2.2" on the top using the arrow keys.