$$p = \frac{y_{1}}{x_{1}} = 4;y_{1} = 4x_{1};\frac{1}{x_{1}} + \frac{1}{{4x}_{1}} = \frac{1}{f}/:x_{1};1 + \frac{1}{4} = \frac{x_{1}}{f};\frac{5}{4} = \frac{x_{1}}{f} \bullet f;\ x_{1} = \frac{5}{4}f;x = x_{1} - x;x - o\ ile\ trzeba\ przesunac\text{\ przedmiot}$$

$$\frac{1}{f} = \frac{1}{x} + \frac{1}{y};\ \frac{1}{y} = \frac{1}{f} + \frac{1}{x} = \left\lbrack x - f \right\rbrack/ \bullet xf;\ y = \ \frac{\text{xf}}{\left\lbrack x - f \right\rbrack}\ \rightarrow wyprowadzony\ \mathbf{y}$$