Аннотация:For a regular dynamical system governed by ordinary differential equations formulas for expansion of the Lyapunov exponents (LEs) with respect to small change in parameters are derived and expressed through the derivatives of the LEs with respect to parameters and approximation of evolution matrix with averaging method. We consider discrete QR algorithm for computing all of the LEs and obtain approximate change of the LEs if there is a small variation of system parameters. These novel LE approximations could simplify the analysis of system's behavior in the space of parameters.