Tested tool guide
Tested browser tools
Checked August 16, 2026
What Derivative Visualizer does, with a checked example
Derivative Visualizer plots an entered function together with its derivative, then draws a tangent line at a movable point on the original curve. Animating that point shows how the tangent's slope changes and how each slope becomes a value on the derivative graph. The key distinction is that the vertical coordinate on f'(x) represents slope, not the height of f(x). A high function value can therefore have a zero, negative, or positive derivative.
Worked example
A concrete input and expected output from the current implementation.
Input
Function: x^2; tangent point: x = 2
->
Expected output
The function point is (2, 4), the derivative graph is f'(x) = 2x, its value at x = 2 is 4, and the tangent line is y = 4x - 4.
Differentiating x^2 gives 2x, so the slope at x = 2 is 4. A line with slope 4 through (2, 4) satisfies y - 4 = 4(x - 2), which simplifies to y = 4x - 4.