Could someone explain this statement to me?

[Centurion]

To emphasize that f'(a) is the rate of change of f(x) as the variable x changes, we call f'(a) the derivative of f with respect to x at x = a. When the function y - s(t) represents the position of an object, the derivative x'(t) is the velocity.

 

[soroban]

Hello, Centurion!

Very confusing . . .
There are typos, and a strange and sudden change of variables.

To emphasize that f'(x) is the rate of change of f(x) as the variable x changes,
we call f'(a) the derivative of f(x) with respect to x at x = a.

When the function y - s(t) represents the position of an object, the derivative x'(t) is the velocity.
. . . . . . . . . . . . . . . ?

It meant to say:

When y = x(t) represents the position of an object,
. . the derivative, y' = x'(t), is the velocity of the object.


Note: How come LaTeX is offline? .