f(x) = x^2drag the point along the curve
f'(x)traced only where you have dragged
a
1.000
f(a)
1.000
f'(a)
2.000
The slope of the tangent line above IS the height of the dot below. Where the tangent runs flat, the dot crosses the zero line. Drag from end to end of the curve to trace as much of the derivative graph as the point can reach.
Tangent Line Tracer: Watch the Derivative Appear from CalcLearn, free AP Calculus study tools.