EN
The paper is the first of three parts that present methods for building a dynamic general equilibrium model. The presentation includes details of micro-economic optimisation problems, ways of solving them and techniques for deriving first order conditions. The representative household maximises the expected, discounted sum of utilities that are a function of consumption and labour. The solution to the problem leads to the Euler equation, which links output to the interest rate and inflation. Other optimality conditions set optimally the consumption/labour ratio and the consumption allocation over time. The second part of the paper examines the profit maximisation of the final producer of a good that is needed to obtain demand functions for the intermediate goods, which are treated as exogenous by intermediate producers. All derived equations appear in the standard New-Keynesian model.