TeX джерело:
\begin{array}{l}\Delta f = f({x_0} + \Delta x) - f({x_0}) = 3{({x_0} + \Delta x)^2} + 2 - 3x_0^2 - 2 = \\ = 3x_0^2 + 6{x_0}\Delta x + 3\Delta {x^2} + 2 - 3x_0^2 - 2 = 6{x_0}\Delta x + 3\Delta {x^2} = \Delta x(6{x_0} + 3\Delta x)\end{array}