Mathematics - Calculus - Differential - Introduction to derivatives - Tangent Line Explorer

Show the graph of f(x)=x². A draggable point moves along the curve. At each position, the tangent line is drawn. Display the slope of the tangent line. At x=1, slope=2. At x=2, slope=4. At x=3, slope=6. At x=-1, slope=-2. Student notices: the slope at x is always 2x! This IS the derivative: f'(x)=2x