摘要:The investment takes the form of sums of money spent for the acquisition of capital goods, changes in business inventories, and the purchases of new residential housing that are not currently consumed, but will be used in the future for the growth of the wealth. The work covered by this study aims to identify the model that presents, in the best possible way, the method of investment’s calculation and to determine the factors of influence. In the first part, the investment is analyzed as a linear function dependent on the interest rate; and the second part implies a new model for determining long-term investments.