Various equations are used in structural analysis to determine internal forces. Typically, different formulas are applied to different sections of a structure to calculate forces or construct shear and moment diagrams. For the convenience of subsequent stress–strain analysis, it is preferable to use a single expression in which all internal forces are represented by one unified equation. Despite the availability of modern structural analysis methods utilizing specialized computational software, the analytical form of force representation offers undeniable advantages over purely numerical methods. Using the example of a simple beam under various loading conditions, this work outlines general rules for formulating equations that express internal forces as a unified expression. The availability of a single equation that allows force determination at any cross-section of a structure enables a clear assessment of the overall stress–strain distribution, the identification of critical areas, the determination of the most vulnerable sections, the selection of an optimal arrangement for supports and hinges, efficient force redistribution management, and ultimately the choice of the most rational structural solution. Efforts expressed as analytical formulas can be computed using off-the-shelf calculation software, without requiring specialized computational complexes.