f(x) =
secant (slope = difference quotient)tangent at a (slope = f'(a))
1.00
\frac{f(1) - f(0)}{1} = \frac{1 - 0}{1} = 1
h
1.00
difference quotient
1.0000
f'(a) exact
0.0000
Drag the amber point (or shrink h) and watch the secant pivot into the ghost tangent.
Secant to Tangent: The Limit Definition, Made Physical from CalcLearn, free AP Calculus study tools.