Let's calculate f(1)
f(x) = x³ - x
f(0) = 1³ - 1
f(0) = 0
So the point (1, f(1)) is the point (1,0)
Let's calculate f(2)
f(x) = x³ - x
f(2) = 2³ - 2
f(2) = 8 - 2
f(2) = 6
So the point (2, f(2)) is the point (2,6)
We plot those points:
Next we draw the graph (in red) and the secant line (in green):
That's the equation of the green secant line.
Edwin