What’s a Derivative?
A more helpful question may be
“What question does a derivative answer?”
Suppose the a variable y depends on x (so that y is a function of x).
Question: If x changes from 102 to 103.4, how much does y change?
Answer: You need the derivative.
Change in y (Derivative) (Change in x)
(Change in x) = = 103.4-102 = 1.4.
(Change in y) = Derivative 1.4.