Current function:
f(x) = x²
Everything stays inside the safe plotting area
Function
Secant
Tangent
-4
-3
-2
-2
-1
0
1
2
2
3
4
-4
-2
0
2
4
6
8
10
12
Δx
Δy
B
A
Slope at a point
secant = Δy / Δx · tangent = f′(x) · function = x²
f′(1.00) = 2.000