Instruction
1
Find the increment of the function: Δf = f(x0+Δx) - f(x0). Find the ratio of the increment function to increment of argument: Δf/Δx = (f(x0+Δx) - f(x0))/Δx. It is assumed that Δx tends to zero. This will be the derivative of function at point x0. In practice, first find a General formula for the derivative function and then substitute the specific value of the argument.
2
For example, f(x) = x^3 - 2x^2 + x + 1, we need to find the derivative at point x = 4.
Find the derivative f(x) = 3x^2 - 2*2x + 1. Find the derivative of f'(4) = 3*4^2 - 4*4 + 1 = 48 - 16 + 1 = 33.