Engineering Handbook/Calculus/Change Variable

Change Variable
Let x be the integer variable then the change in variable x can be defined as
 * $$x - x_o = \Delta x $$

Therefore
 * $$ x = x_o + \Delta x$$

if there is a function of x f(x) then a change in variable x causes a change in the function as
 * $$\Delta f(x) = f(x) - f(x_o)$$

Then
 * $$ f(x) = f(x_o) + \Delta f(x) $$